Hotels and resorts also feature in the top 19, while two residential towers make an appearance — one of which is used by just a single family.
There are just two office skyscrapers in the ranking, suggesting that more specialised developments require more money.
Most were built in this century, but a few were opened in the late 1980s and early '90s, with their inflation-adjusted prices soaring accordingly.
Check out the list below:
19. Trump Taj Mahal, Atlantic City — $1.9 billion (£1.3 billion). He may be vying for the US presidency these days, but Trump made his name as a property tycoon. His East Coast casino was built for just over a billion dollars in 1990. With 26 years of inflation, that's a lot more.
18. Taipei 101, Taipei — $2 billion (£1.36 billion). This was the world's tallest building when it was unveiled in 2004, and it's designed to withstand earthquakes and typhoons. The architecture, based on a pagoda, is said to symbolise the "renewal of time."
17. The Palazzo, Las Vegas — $2.05 billion (£1.4 billion). The first of many Vegas casinos on the list, the Palazzo has some of the nicest hotel rooms money can buy, not to mention the biggest at 720 square feet per room.
16. Bank of China Tower, Hong Kong — $2.1 billion (£1.43 billion). One of Southeast Asia's most iconic skyscrapers, the BOC Tower was completed in 1990 for $1 billion. At today's prices, that's just over $2 billion.
15. Princess Tower, Dubai — $2.2 billion (£1.5 billion). Skyscraper construction has exploded in Dubai over the last decade, with the Princess Tower — the tallest in the picture — currently the second highest after the Burj Khalifa. Unlike most on the list, it's exclusively residential.
14. Bellagio, Las Vegas — $2.3 billion (£1.57 billion). Owned by MGM Resorts International, the Bellagio opened in 1998 on the site of the old Dunes casino. It boasts over 2,000 hand-blown glass flowers on its lobby ceiling and almost 1,000 rooms.
13. Antilla, Mumbai — $2.5 billion (£1.7 billion). One of the more controversial buildings on the list, Antilia was built by Indian billionaire Mukesh Ambani on the site of an orphanage. Its opulence has been called distasteful in a city with so much poverty.
12. City of Dreams, Macau — $2.75 billion (£1.9 billion). The City of Dreams opened in 2009 as an entertainment resort. Attractions include the "Vquarium," in which viewers are surrounded by four giant screens for immersive underwater simulations.
11. Venetian, Macau — $3 billion? (£2 billion). Just next door to the City of Dreams is the Venetian, which gives Vegas casinos a run for their money. It officially opened in 2007 with over 3,000 suites, and even more slot machines.
10. Wynn Las Vegas, Las Vegas — $3.3 billion (£2.25 billion). The Wynn is considered one of the best hotels in the world, with five-star ratings from AAA, Mobil, Michelin, and just about any other ranking agency you can think of. It was also the first high-rise to have automated window-cleaning.
9. Freedom Tower, New York City — $4 billion (£2.7 billion). Officially called One World Trade Center, the Freedom Tower was built on the site of the 9/11 attacks and opened in 2014 to become New York's tallest building and a symbol of defiance in the face of terrorism.
8. The Cosmopolitan, Las Vegas — $4.1 billion (£2.8 billion). The most expensive American casino resort on the list, the two Cosmopolitan towers house 3,000 rooms as well as
the Marquee Nightclub & Dayclub, which was at one point the top-grossing nightclub in the US.
7. Parliament House, Canberra — $4.2 billion (£2.9 billion). Australia's Parliament House was completed in 1988 for over 1 billion Australian dollars. In today's money, that comes to over US $4 billion. The building has 4,700 rooms and the lighting powered? by solar energy.
6. Resorts World Sentosa, Singapore — $5.4 billion (£3.7 billion). One of the premier tourist attractions in Asia, the Resorts World Sentosa features a Universal Studios park, an Adventure Cove Waterpark, and the world's largest oceanarium. It requires over 10,000 employees to run daily.
5. Emirates Palace, Abu Dhabi — $6 billion (£4.1 billion). The most expensive luxury hotel ever constructed, the Emirates Palace opened in 2006 in a bid to show off Arabian culture to the whole world. It's so luxurious that it describes itself as "beyond 5 stars." Fans of "Furious 7" will also recognise the exterior.
4. Marina Bay Sands, Singapore — $8 billion (£4.5 billion). The most expensive casino ever constructed, the Marina Bay Sands opened a year behind schedule in 2010 thanks to material and labour shortages. Attractions include a spectacular "sky park" and infinity pool on the giant roof.
3. Tokamak Reactor, France — $14 billion (£9.7 billion). The only research facility on the list, the Tokamak reactor in Cadarache, France, uses a torus shape (pictured below) to create powerful magnetic fields to stabilise and confine plasma. There are now several such reactors all over the world.
2. Abraj Al Bait, Mecca — $15 billion? (£10.2 billion). The giant clock tower that overlooks Mecca in Saudi Arabia opened in 2012 after almost a decade of construction. The tower attracted controversy for being built on the Ottoman-era Ajyad Fortress, an Islamic heritage site.
1. The Grand Mosque, Mecca — $30 billion-plus (£20.5 billion-plus). The world's most sacred mosque is also the world's most expensive construction, though with so many upgrades it's impossible to put an accurate figure on it. In 2011, a $10 billion project to add over 4 million square feet of space was announced. It currently covers over 88 acres and hosts over 5 million Muslims every year.