The government of the custodian of the two holy mosques decided to build a railway in the southern section of the holy sites. The region gets super hot during Hajj, so spending a lot of time outside traveling between sites can be risky. Despite that, the whole thing was completed in just two years, which is incredibly fast if you think about the scope. And then in 2011, it carried nearly 4 million pilgrims around between these holy sites.