This video by Rebel Media claims at 4.10:
Saudi Arabia has 100,000 air-conditioned tents sitting empty in the desert. They can hold half a million people ...
Is it true?
Yes, the city of Mina has 100,000 air-conditioned tents. They are empty much of the year.
Mina is a small city located inside a low lying valley in the province of Makkh, in western Saudi Arabia, about 8 km to the east of the Holy city of Mecca. Inside the 20 square km valley, tents cover every open space, as far as the eye can see, neatly arranged, row after row. It is in these tents Hajj pilgrims stay overnight during the five days of each Haj season. For the rest of the year, Mina remains pretty much deserted.
There are more than 100,000 air-conditioned tents in Mina providing temporary accommodation to 3 million pilgrims. The tents measure 8 meters by 8 meters and are constructed of fiberglass coated with Teflon in order to ensure high resistance to fire. Originally pilgrims brought their own tents which they would erect in the flat plains of Mina. After Hajj is over, the tents would be dismantled, everything packed and taken back. Then sometime in the 1990s, the Saudi government installed permanent cotton tents relieving pilgrims of the burden of having to carry their own camping equipment. But after a massive fire that swept through the tent city killing nearly 350 pilgrims in 1997, the current permanent fire-proof city was built.
Wikimedia offers a picture:
Photo from mountainside of the tented areas covering the Plain of Mina, Saudi Arabia
A satellite view of the tents shows the enormous extent of this tent city. (Hat tip: @Janik Zikovsky)
The existence of this tent city should not be interpreted as support for the rest of the propaganda in the Rebel Media video. For example, we have had answers here before that explain that the "zero refugees" is explained by legal definitions of refugees rather than a lack of support of Syrians. The existence of the tents, designed to handle the annual pilgrimage, doesn't imply that the logistics of using them to support 500,000 permanent residents is easy.