Richest: Warren Buffett — $144 billion

The finance and investments industry has been the biggest maker of fortunes. Most of the wealthiest individuals in this category are founders of hedge funds, mortgage lenders, VC, and investment firms.

Some are heirs to founders, such as the grandchildren of Fidelity founder Edward Johnson II.

Richest: Elon Musk — $908 billion

Technology has been a massive maker of fortunes; the nine richest in this category are wealthier than Warren Buffett.

Many are founders of big-name tech companies, as well as software and computer hardware firms. The AI boom has brought several newcomers to the list, including OpenAI cofounder and president Greg Brockman.

Richest: (Tie) Jacqueline and John Mars — $50.3 billion

From Chick-fil-A to Tito's Vodka, there are plenty of household-name brands in this category.

Others made their fortunes in the non-consumer parts of the food and beverage industry. These include J. Christopher Reyes and Jude Reyes, who cochair the food and beverage distribution firm Reyes Holdings, or Harry Stine, who made his fortune licensing soybean and corn genetics.

Richest: Rob Walton & family — $132 billion

Like food and beverage, household names dominate the fashion & retail category. Walmart alone is listed as the source of wealth of eight people in this industry.

Other sources of retail wealth are less obvious. Jimmy and Bill Haslam's fortunes largely derive from the truck stop chain Pilot Flying J, which their father founded.

Richest: Lyndal Stephens Greth & family — $30 billion

Oil tycoons and their families make up the bulk of this list. And it's not just those with stakes or roles in companies involved in production, but also pipelines and refineries.

Richest: Stephen Ross — $21.5 billion

America's wealthiest real-estate magnates built their fortunes through all kinds of properties. Jeff Greene, for example, made billions investing in credit default swaps tied to subprime mortgage-backed securities before the financial crisis.

With an estimated net worth of $7 billion and much of his wealth tied to real estate, President Donald Trump is also included in this category.

Richest: Rupert Murdoch & family — $25 billion

Legacy media, such as cable and satellite television, continue to dominate this category. However, some billionaires built their fortunes through other kinds of media, including Gabe Newell, who cofounded video game developer Valve.

Movies have minted others, such as award-winning director Steven Spielberg and "Star Wars" creator George Lucas.

Richest: Stanley Kroenke — $27.6 billion

For many people in the sports category, team ownership is more of a second act, rather than the original source of their wealth.

For example, before they bought teams, Arthur Blank cofounded Home Depot, Stephen Bisciotti made his fortune in talent management, and Arturo Moreno made his money from billboard advertising.

There are some exceptions, such as Michael Jordan, whose basketball career was the origin of his wealth.

Richest: Thomas Frist, Jr. & family — $33.6 billion

Aside from the category's richest entry, Thomas Frist Jr. and family, whose wealth comes from hospitals, most of the others made or inherited their fortunes in pharmaceuticals, medical devices, and medical equipment.

One, Patrick Soon-Shiong, developed the chemotherapy drug Abraxane.

Richest: Steven Rales — $8.7 billion

Manufacturing spans a variety of industries, from packaging materials to defense.

Some big fortunes come from everyday products you might not expect. Cleaning products alone account for four people on the list, all of whom are heirs to SC Johnson, whose products include Windex and Glade.

Richest: Micky Arison & family — $11.5 billion

Aircraft leasing, cruises, and self-storage are just some examples of services that have turned people into billionaires.

Lucrative service companies aren't necessarily the most glamorous. Gary Rollins, for example, is executive chairman emeritus of pest control firm Rollins, which was founded by his father.

Richest: Ernest Garcia, II — $24.3 billion

In the US, automotive fortunes are less about manufacturing cars and more about selling, servicing, and moving them.

Forbes 400 member Dan Friedkin, for example, owns Gulf States Toyota, while Shahid Khan owns auto parts supplier Flex-N-Gate.

Richest: Julia Koch & family — $84.6 billion

Diversified means fortunes that don't neatly come from one industry. Members of the Koch family, which has stakes in the conglomerate Koch, dominate this segment.

Richest: Brad Jacobs — $13.3 billion

The businesses that move products through the supply chain are among the most essential to day-to-day life, and can be worth billions.

For example, Johnelle Hunt, who cofounded transportation and logistics firm J.B. Hunt Transport Services, is worth $6.6 billion.

Richest: Diane Hendricks — $23.6 billion

All three members of the Forbes 400 in the construction and engineering industry are self-made billionaires.

Diane Hendricks cofounded building-supply distributor ABC Supply with her late husband, Ken Hendricks. Mike Hollingshead founded concrete maker Smyrna Ready Mix, while Robert Clark founded construction firm Clayco.

Richest: Miriam Adelson & family — $33.5 billion

With just two members categorized in the Forbes 400, gambling and casinos are the smallest category.

Miriam Adelson's late husband, Sheldon Adelson, was the founder of casino company Las Vegas Sands, while Jon Yarbrough founded casino producer Video Gaming Technologies.

Phil Ruffin, who Forbes categorized as diversified, made his wealth from a mix of casinos and real estate.

The restaurant was advertising the chain's new chicken tenders on its modern-looking exterior.

This is one of roughly 13,600 McDonald's locations in the US, according to the company. That's far more than its number of restaurants in the UK, where it has around 1,500 locations.

During our visits, the New York location also felt more modern and pared back, while the London restaurant featured brighter colors and more playful design details.

That kind of highly visible security message felt distinctly New York.

There was one security officer outside the McDonald's in London, though there were no big security messages like in the New York restaurant.

Inside, the restaurant had self-order kiosks, a counter for pickup orders, and plenty of seating for customers eating in or taking food to go.

The meal came in McDonald's signature brown paper bag and included a spicy chicken sandwich, medium fries, an apple pie, and a medium-sized fruity pink drink.

It cost $15.18, excluding tax.

It was also topped with pieces of freeze-dried strawberry. Erin enjoyed the balance of sweet watermelon, tart strawberry flavoring, and lemonade, but the dried fruit pieces made the drink awkward to sip — she kept getting chunks in her mouth.

Still, it was a refreshing, summery beverage she'd order again, ideally without the strawberry topping.

The sandwich is one of McDonald's biggest attempts to compete in the fast-food chicken wars.

First launched nationwide in February 2021, the sandwich has become a staple on McDonald's menu and can even compete with fast-food classics like Chick-fil-A's famous chicken sandwich.

It looked far more substantial than the more basic chicken sandwiches often associated with McDonald's, like the McChicken.

Erin was also impressed by the size of the chicken filet, which was about the same size as her palm.

It stayed crispy beneath the toppings and delivered a savory, black-peppery flavor that gave each bite a little extra kick, on top of the creamy, spicy sauce that left a slight lingering heat.

The fries were thin, salty, and hot — the familiar classic that remains one of the chain's most consistent menu items. The US order came with a generously filled carton that was large enough to share, though Erin had no trouble working her way through most of it.

The tangy, creamy dipping sauce gave the salty fries an extra punch of flavor and made for an especially satisfying final bite.

The hand pie had a flaky, golden-brown exterior and came in a sleek purple sleeve. It cost $1.99, excluding tax.

Inside, the soft apples were sweet and caramelized, giving the dessert a cozy, almost homemade flavor that made it a satisfying end to the meal.

Erin did think the pastry could have been a bit less doughy and a bit more flaky to better resemble a real apple pie.

This McDonald's had lots of emoji faces on its windows to advertise McHappy Day, a charity fundraiser for Ronald McDonald House UK on September 26.

Roya went to McDonald's on September 22, which was the first day of the World Menu Heist.

These are popular McDonald's items from around the world, made into limited-edition items in the UK and Ireland.

Inside, you can order at the counter or at the self-service kiosks. A lot of people pick up their orders after placing them on the McDonald's app.

Roya opted for the "eat in" option, so the meal came on a tray. Adding a paper bag at this McDonald's would have cost an extra 13 cents.

The meal cost £11.38 ($15.18) including tax.

The drinks we ordered weren't a direct match: Erin ordered McDonald's strawberry watermelon refresher in New York, which was not on the UK menu when we checked, while Roya tried the UK-only guava Sprite Zero.

This drink was part of the World Heist Menu. Roya found it refreshing and liked the extra tang that the guava-flavored syrup added to the Sprite.

There were also some differences in the portion sizes and sugar content between our two drinks.

A medium soda at McDonald's is much bigger in the US, where it holds 21 fluid ounces, compared with 13.5 fluid ounces in the UK.

McDonald's UK still sells some sugary drinks, but its soft-drink menu leans more heavily on zero-sugar options, including Sprite Zero. That reflects the UK's Soft Drinks Industry Levy, introduced in 2018 to encourage manufacturers to cut sugar from beverages; drinks with more than 5 grams of sugar per 100 milliliters are subject to the tax.

In the US, the McCrispy is marketed as a sandwich, whereas in the UK, it's more commonly referred to as a burger.

The McCrispy was launched in 2022 after the discontinuation of the very popular Chicken Legend. The spicy version launched this year.

Roya thought the chicken filet was substantial — much bigger than the beef burgers typically sold at McDonald's.

Different from the US potato roll, the bread is a sourdough-style bun topped with sesame seeds.

McDonald's varies its recipes and menus across countries to comply with local regulations and cater to customer tastes. For example, Canadian McDonald's has a maple-and-cheddar chicken burger, another item that featured on the World Heist Menu.

The filet itself was moist, with a crispy, crunchy batter that Roya thought had a satisfying kick of heat. This was different from the US version, which has a lighter, less-crunchy breading without any heat — all the spicy flavor comes from the sauce.

She thought there could have been more spicy mayo and pickles, like in the US, to add a bit more texture. The lettuce, while adding a nice freshness, didn't do much for the dryness.

While the London-based reporter always enjoys McDonald's fries, she thought they could have been crispier this time — they were a little floppy.

Roya, who prefers her food saltier, added a salt sachet to the fries. Nonetheless, they came out hot and were a satisfying companion to the burger.

McDonald's UK says it has reduced the fat, salt, sugar, and calories in its menu since 2020, which may contribute to the milder flavor compared with the US fries.

American McDonald's fries also have beef flavoring added to them to replicate the old-school taste of frying in beef tallow.

Ketchup and barbecue sauce are usually available from dispensers in most McDonald's in the UK. Roya opted for ketchup, which added a lip-smacking tang to the fries.

Ranch is not as popular or well-known in the UK, but McDonald's UK did have it as a limited-edition dip this summer.

The apple pie in this London McDonald's costs £2.29 ($3.05), including tax.

Roya's UK apple pie was fried and sealed like a hand pie, unlike the lattice-topped baked pie sold in the US. The UK version closely resembled how McDonald's in the US used to make its apple pies before it switched to a baked, not fried, version in 1992.

The US version got another update in 2018, when the latticed crust was introduced, and the chain switched to a sliced apple filling with cinnamon.

Because the apple pie is deep-fried, it makes for a very crunchy outside, which complements well with the warm, soft, and sweet filling.

The fried batter does make it feel a little heavier for a midday dessert, but it's worth it for the crunch.

From the design of the restaurant to the actual menu, there were some key differences between the two locations. Even similar items differed in terms of ingredients and size.

We were surprised that our meals were the exact same price, and the chicken sandwiches were pretty similar in portion size. However, the sodas were very different in size, with the US medium drink being much larger, and the UK apple pie looked more like a fried strudel than a lattice pie.

The chicken sandwich in the US also had more sauce and a saltier flavor, which Roya thought the UK version lacked.

From the restaurant design to the last bite of pie, our cross-Atlantic McDonald's taste test proved that "the same" order can mean something very different depending on where you are.

Only about 31% of trains on the Tube network have passenger air conditioning, according to Transport for London (TFL). As soon as a heat wave hits, I cannot ride the Tube without carrying blotting paper and a handheld fan.

Some lines are notorious for how hot they get. Having to take the Central Line in the summer will elicit sympathy from any Londoner. The London Standard reported that it reached almost 103 degrees during the recent June heat wave.

With that in mind, you may also be surprised to learn that in 1926, the London Underground was advertised as "cooler below" on a hot day.

Unlike the hard plastic seats in most American public transport, Tube seats are covered in a woolen fabric called moquette.

It's been used on the Tube since 1920 because it hides wear and tear and dirt, and also because it's durable.

Admittedly, it does gross me out a bit, even though it gets cleaned. But it's definitely more comfortable than plastic, at least.

While the New York City subway has a flat fare, the cost of a journey on the Tube varies depending on how far you travel.

London's transport network is split into fare zones, from the most central to the farthest out: Zones 1 to 9. People here often joke that the zone you live in also determines how much of a "true" Londoner you are.

For example, a single journey within Zone 1 will cost you £3 at off-peak hours, and £3.10 at peak hours. However, if you travel from Zone 6 to 1, or vice versa, it will cost you between £4 and £5.90.

Rush hour is known as peak time on the Underground and other rail services.

Peak time is Monday to Friday, except public holidays, between 6:30 a.m. and 9:30 a.m., and between 4 p.m. and 7 p.m. Fares are higher at these times.

In addition to saving a bit of money, I would recommend avoiding these times for travel. Carriages can get crammed, and people can be unforgiving if you're carrying a large suitcase or walking too slowly.

With all these varying fare prices, you have to tap your card, contactless, Oyster, or physical ticket in and out of the Tube.

Often, there are barriers upon both entry and exit, so you wouldn't miss this, but sometimes there aren't. In these stations, you have to look for a yellow card reader to tap out.

If you don't tap out, you will be charged the maximum fare for that line. I've had this happen to me before, but luckily, you can request a refund from TFL if it happens again.

If you like your personal space, you might be pleased to know that most Tube carriages have an armrest between seats.

However, despite their name, I see them as more of a separation barrier than an actual armrest. Resting your arms on these is a faux pas (unless you absolutely have to) if there are people sitting on either side of you.

While you may be expecting to descend deep underground when taking the Tube, this isn't always the case. Despite its name, most of the London Underground's stations are above ground. I find this is handy for getting service.

The Waterloo & City and Victoria lines are the only two fully underground tube lines.

My ultimate word of advice for anyone coming to London is to never stand on the left-hand side of the escalator. The left side is for people walking up or down in a hurry.

It's an efficient system that has saved me from being late hundreds of times. You will be asked to move aside if you break this rule.

If you like all things spooky and historical, I recommend checking out the London Transport Museum, which offers tours of disused Tube stations, passenger corridors, and tunnels.

Some of these spaces have been used as sets for TV shows and films, including Skyfall and Sherlock.

London is not quite the city that never sleeps. I have rarely taken the Tube past midnight and instead rely on Ubers and night buses to get me home.

Only five Tube lines run 24-hour services: Central, Jubilee, Northern (Charing Cross branch), Piccadilly, and Victoria. The Windrush line, which is part of the London Overground, also has a night service.

The Night Tube is also only open on Fridays and Saturdays.