From super-tall skyscrapers to impossibly lavish casino resorts, constructing mega buildings is not a cheap task. It will set you back millions and even billions of dollars. A building is briefly defined as a structure with a roof and walls, standing more or less permanently in one place, such as a house or factory. Airports are excluded as their construction cost includes runways and systems.
Here are the top 20 most expensive buildings in the world.
| Rank | Building | Country | Nominal cost |
| 1. | Masjid al-Haram | Saudi Arabia | $100 billion |
| 2. | ITER | France | $25 billion |
| 3. | Flamanville 3 | France | $21.93 billion |
| 4. | Akkuyu Nuclear Plant | Turkey | $20 billion |
| 5. | Abraj Al Bait | Saudi Arabia | $16 billion |
| 6. | Olkiluoto 3 | Finland | $12.4 billion |
| 7. | Mochovce Nuclear Power Plant (block 3 & 4) | Slovakia | $7.61 billion |
| 8. | Nya Karolinska Hospital | Sweden | $6.61 billion |
| 9. | Željava Air Base | Croatia | $6 billion |
| 10. | SoFi Stadium | United States | $5.5 billion |
| 11. | Marina Bay Sands | Singapore | $5.5 billion |
| 12. | Apple Park | United States | $5 billion |
| 13. | Resorts World Sentosa | Singapore | $4.93 billion |
| 14. | Wynn Palace | Macau | $4.2 billion |
| 15. | The Cosmopolitan | United States | $4.1 billion |
| 16. | One World Trade Center | United States | $3.8 billion |
| 17. | Lotte World Tower | South Korea | $3.11 billion |
| 18. | Emirates Palace | United Arab Emirates | $3 billion |
| 19. | Palace of the Parliament | Romania | $3 billion |
| 20. | Wynn Resort | United States | $2.7 billion |
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