We all know that buildings don't always turn out like the renderings. Last-minute changes and real-life materials can all cause discrepancies between the vision and reality of a project. In our weekly Flash Forward Friday feature, we take a look at how different projects stack up.

Mecca in Saudi Arabia is considered the holiest city in the religion of Islam. The annual Islamic pilgrimage known as Hajj is a ritual that all physically and financially able Muslims must undertake at least once in their lifetimes. To accommodate an increasing Islamic population, Mecca's infrastructure has needed to expand. Since opening in 2012, the megatall Abraj Al-Bait Towers have served as an empowering symbol of a modernized Mecca. 

Abraj Al Bait Towers, image via Dar Al-Handasah Shair & Partners

The Makkah Royal Clock Tower is the centrepiece of the complex, defined by a five-star Fairmont hotel and the world's largest clock face. Saudi Arabia's largest construction company, Saudi Binladin Group, originally proposed a 734-metre height for the building, though it was confirmed three years later that the building would instead climb 601 metres. That's still high enough to make it the third tallest building in the world. 

Abraj Al Bait Towers in 2012, image by King Eliot via Creative Commons

The $15 billion finished building stayed quite true to the project rendering. The colour of the facade is perhaps a bit more muted than initially suggested, though the finer architectural details of the massive complex were achieved. A series of sky bridges, as depicted in the rendering, connect the adjacent structures to the main clock tower. The 23-metre-high golden crescent spire encompasses an observation deck at the bottom level, providing unmatched views of the holy site.  

We will return next Friday with another comparison!