On a recent trip to Morocco, we visited the relatively new (1960s) Mosque in Casablanca. It houses 25,000 people inside for prayer, another 80,000 in the courtyard, to give you some idea of size.
Many of the windows and doors inside allowed light in, and this gave me the wonderful graphic pattern that reflected off the highly polished floor (see photo above). Beyond those doors and windows lie the Atlantic Ocean and America, feeling very far away in this moment. We all learned the value of our cameras' high ISO in there, since no tripods were allowed.
Outside, there were wonderful details and arches (see below). We focused on using those arches as framing elements in our compositions. Then we waited for interesting things to happen, like this woman in a fuschia-colored jelaba, the customary robes of Morocco, to walk through.