Mecca

Pilgrimages to holy sites around the world have caused large amounts of waste and pollution because of the large amount of people gathering together for one event and consumeristic habits, writes George Webster for CNN

Millions have been in the tent city of Mina in Mecca for the annual Hajj pilgrimage. Though the crowds are temporary, the infrastructure built to handle them is permanent.

Millions of religious pilgrims travel to Mecca in Saudi Arabia every year for the Hajj. Officials there have been updating the city to better handle the crowds.

New plans have been released by Gensler that show a proposed expansion of the holy city of Mecca.

Big-name architects -- including Norman Foster and Zaha Hadid -- have reportedly been tapped to be part of a team of designers tasked with redesigning the Islamic holy city of Mecca and its mosque.