Yesterday we went to the Hassan II Mosque in Casablanca, which has the biggest minaret in the world and is the 7th largest mosque in the world. The inside is massive, and the guide told us they can fit more than 100,000 people (which usually happens during Ramadan).
It is also literally on the Atlantic Ocean. There is this huge plaza, and just on the side there is a small beach with kids just jumping off one of the mosque walls right into the water. The whole complex was really beautiful.