In brief
- The Grand Mosque in Mecca is the most expensive building, with expansions estimated at about $100 billion.
- The ITER fusion reactor in France is estimated at more than $20 billion.
- Abraj Al Bait, next to the Grand Mosque, cost about $15 billion.
- Marina Bay Sands began an $8 billion expansion in July 2025.
As of October 2026, the most expensive building ever constructed is the Grand Mosque (Masjid al-Haram) in Mecca, with successive expansions estimated at about $100 billion. It is followed by the ITER fusion reactor in France and the Abraj Al Bait towers in Mecca. Casinos and hotels make up most of the rest.
Costs below are the construction figures most widely reported at the time each project was finished, in US dollars unless stated. They are not adjusted for inflation, so older projects such as Australian Parliament House look cheaper than they would in current money.
The 10 most expensive buildings at a glance
| Rank | Building | Location | Reported cost | Opened |
|---|---|---|---|---|
| 1 | Grand Mosque (Masjid al-Haram) | Mecca, Saudi Arabia | About $100 billion (all expansions) | Ongoing |
| 2 | ITER Tokamak | Saint-Paul-lès-Durance, France | Over $20 billion (estimate) | Under construction |
| 3 | Abraj Al Bait | Mecca, Saudi Arabia | About $15 billion | 2012 |
| 4 | Marina Bay Sands | Singapore | About $5.7 billion | 2010 |
| 5 | Resorts World Sentosa | Singapore | S$6.59 billion (about $4.9 billion) | 2010 |
| 6 | The Cosmopolitan of Las Vegas | Las Vegas, USA | $3.9 billion | 2010 |
| 7 | World Trade Center Oculus | New York, USA | About $3.9 billion | 2016 |
| 8 | Emirates Palace | Abu Dhabi, UAE | About $3 billion | 2005 |
| 9 | Wynn Las Vegas | Las Vegas, USA | $2.7 billion | 2005 |
| 10 | Australian Parliament House | Canberra, Australia | A$1.1 billion | 1988 |
1. Grand Mosque (Masjid al-Haram): $100 billion
Masjid al-Haram surrounds the Kaaba, the holiest site in Islam, and receives millions of pilgrims during Hajj and Umrah. The figure of about $100 billion is an estimate of the total spent on the large expansion programmes carried out by the Saudi government over several decades, not a single construction contract.
Also readPatek Philippe 1436 in Steel Leads Phillips Geneva at CHF 4mThe most recent phases added new prayer halls, courtyards, bridges and services to raise capacity. The mosque is never fully closed for work, so construction is carried out in stages around worshippers.
2. ITER Tokamak: over $20 billion
ITER is an international fusion energy experiment being built in the south of France by a group of members that includes the European Union, China, India, Japan, South Korea, Russia and the United States. Much of the funding is given as parts rather than cash, so there is no single official total.
Published estimates for construction run above €18 billion. In July 2024 ITER announced a new baseline that added about €5 billion and moved first plasma research operations to 2034, with deuterium-tritium operation expected in 2039.
3. Abraj Al Bait: $15 billion
Abraj Al Bait is a complex of seven towers next to the Grand Mosque. Its central Makkah Royal Clock Tower is over 600 metres tall and its four clock faces are each about 43 metres across, among the largest in the world.
The complex, completed in 2012, houses hotels, apartments, a shopping centre and prayer space. Its cost is widely reported at about $15 billion, with some sources citing higher figures.
4. Marina Bay Sands: $5.7 billion
Marina Bay Sands in Singapore was developed by Las Vegas Sands and designed by architect Moshe Safdie. Its three 55-storey hotel towers are joined at the top by the SkyPark, which includes the well-known infinity pool.
The resort opened in 2010 at a reported cost of about S$8 billion, or roughly $5.7 billion including land. In July 2025 work began on an $8 billion expansion with a fourth tower of about 570 suites and a 15,000-seat arena, according to CNN.
5. Resorts World Sentosa: $4.9 billion
Resorts World Sentosa, Singapore’s second integrated resort, opened in 2010 on Sentosa Island. It was built by Genting at a reported cost of S$6.59 billion, about $4.9 billion at the time.
The site includes Universal Studios Singapore, a casino, several hotels and a large aquarium.
6. The Cosmopolitan of Las Vegas: $3.9 billion
The Cosmopolitan opened on the Las Vegas Strip in December 2010. Its two towers hold about 3,000 rooms and suites. The project cost $3.9 billion, according to the Las Vegas Review-Journal, which makes it the most expensive resort built on the Strip.
It was financed by Deutsche Bank after the original developer defaulted. The resort was later sold to Blackstone and is now run by MGM Resorts.
7. World Trade Center Oculus: $3.9 billion
The Oculus is the main hall of the World Trade Center Transportation Hub in Lower Manhattan, designed by Santiago Calatrava. It opened in 2016 after long delays.
Its cost of about $3.9 billion, close to double the early budget, made it one of the most expensive train stations ever built. It links PATH trains, several subway lines and a shopping centre.
8. Emirates Palace: $3 billion
Emirates Palace in Abu Dhabi opened in 2005 and was built by the Abu Dhabi government. It has about 400 rooms and suites, a private beach and interiors finished in marble and gold leaf. Its cost is widely reported at about $3 billion.
The hotel is now operated as Emirates Palace Mandarin Oriental. Read more in our list of the most expensive hotels around the globe.
9. Wynn Las Vegas: $2.7 billion
Steve Wynn opened Wynn Las Vegas in April 2005 on the site of the former Desert Inn. It cost $2.7 billion, which the Las Vegas Review-Journal puts at about $3.26 billion in later dollars.
A sister tower, Encore, opened in 2008. The resort is known for its golf course, its art collection and its high-end shopping.
10. Australian Parliament House: A$1.1 billion
Australian Parliament House in Canberra was opened by Queen Elizabeth II in May 1988. It was built partly into Capital Hill and is topped by an 81-metre flagpole.
It cost about A$1.1 billion at the time, which made it one of the most expensive buildings in the world in the 1980s. Allowing for inflation, the cost would be several times higher today.
How we ranked these
We used the construction cost reported by official sources or major news outlets when each building was completed. Where a project is still being built or extended, such as the Grand Mosque and ITER, we used the most recent published estimate. Large infrastructure such as bridges and dams is excluded; see our list of the most expensive bridges ever built.
Sources: ITER Organization, Physics World, CNN, Las Vegas Review-Journal, Christian Science Monitor.
Frequently asked questions
What is the most expensive building ever constructed?
The Grand Mosque (Masjid al-Haram) in Mecca is the most expensive, with its successive expansions estimated at about $100 billion. The figure covers several decades of work by the Saudi government rather than one construction project, and expansion work around the mosque continues.
How much did Abraj Al Bait cost?
Abraj Al Bait in Mecca, home to the Makkah Royal Clock Tower, is widely reported to have cost about $15 billion. The seven-tower complex was completed in 2012 and includes hotels, apartments, a shopping centre and prayer space next to the Grand Mosque.
How much did Marina Bay Sands cost to build?
Marina Bay Sands opened in Singapore in 2010 at a reported cost of about S$8 billion, roughly $5.7 billion including land. In July 2025 Las Vegas Sands began an $8 billion expansion that adds a fourth hotel tower and a 15,000-seat arena.
What is the most expensive hotel on the Las Vegas Strip?
The Cosmopolitan of Las Vegas, which opened in December 2010, cost $3.9 billion to build, according to the Las Vegas Review-Journal. Wynn Las Vegas, opened in 2005, cost $2.7 billion and ranks second among Strip resorts by construction cost.
Why is ITER so expensive?
ITER is a first-of-its-kind fusion reactor built by several countries, and many parts are made to new specifications. Delays and technical problems have raised costs. In July 2024 ITER added about €5 billion to its budget and moved research operations to 2034.
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