Mohammed V Mausoleum, Rabat

Actually, this is not the mausoleum (the building is ouside the picture, on the left).
These columns are the remains of a very big mosque built by sultan Yacoub el-Mansour in the 12th century. The mosque was never completed, and what had been built was then destroyed by an earthquake in 1755.
The place is so huge you can only be impressed by the undertaking of such a construction!