Every year, the Ministry of Haj sets up a tent city to support pilgrims in the city of Mina. Because up to four million pilgrims may be performing the Hajj annually, the tent cities are densely inhabited with 20-40 people per tent. Due to the Mina valley's mountainous topography, 25 tunnels have been constructed in with lengths varying from 200 to 1500m, along with 40 bridges to facilitate pedestrians and traffic. __