Pretty amazing images of the crowd:
According to this article:
The 600m clock-tower we see in the top image “rising like Big Ben on steroids” is the largest in the world, and also has the biggest clock-face in the world. The building it sits above has the largest floor area in the world, housing luxurious hotels, appartments and a “five-story slab of shopping malls”. It stands where an Ottoman fortress once stood, which was demolished (along with the hill it stood on) in 2002 to much international condemnation.
The desperation to be as close to the Kaaba has led to buildings surrounding the mosque being built higher and higher. Mecca has the most expensive real estate in the world (1 square foot of the Grand Mosque sells for up to $18,000).