This is world's costliest building, it is not Mukesh Ambani's Antilia, Buckingham Palace, Burj Khalifa in Dubai, the building is in..., name is...

In the holy city of Mecca, Saudi Arabia, a stunning complex of seven skyscraper hotels has been built just 300 metres from the Great Mosque of Mecca—Islam’s most sacred site. The project aims to modernise the city and support the millions of pilgrims who visit each year for the Hajj pilgrimage.

At the heart of the complex stands the Makkah Clock Royal Tower. It is the fourth-tallest building and sixth-tallest freestanding structure in the world. Built at an estimated cost of £12.6 billion, it is one of the most expensive buildings ever made—about 35 times larger than London’s Big Ben, according to the Daily Express.

The tower’s four-faced clock is the biggest in the world, visible from 16 miles away. Each clock face is 43 metres wide and lit by two million LED lights. Above the clock, large Arabic inscriptions decorate the tower’s four edges.

Construction firms from over ten countries worked on the project. A German firm designed the famous clock. However, due to Mecca’s religious rules, non-Muslims couldn’t enter the city. As a result, some foreign workers, including glazing experts from Poland and Germany, converted to Islam to be part of the on-site team.

The tower was originally planned to be 450 metres high—enough to be the tallest building at that time. But the height was later increased to 600 metres. "Burj Khalifa was also being planned, and when they saw this tower would be 600 metres, they extended theirs to 800 metres," said Mustafa Rasch, CEO of SL Rasch and a former site manager of the project.

The complex was built on the site of the historic Ajyad Fortress, an 18th-century Ottoman citadel. Its demolition in 2002 caused strong backlash, especially from Turkey, due to the site's historical importance.