Hagia Sofia is an amazing piece of architecture and art. It was a church that became a mosque that became a museum. The interior is covered with beautiful stone panels, carved stone, mosaics, and painted plaster. Much of the mosaics were covered with plaster and then painted centuries ago, but the revealed mosaics are intricate and beautiful. The painted plaster is quite beautiful also. The stone panels demonstrate the beauty of natural stone. Besides the actual decorative interior, the actual architectural form of the building with all its domes and arches is gorgeous and also amazing from an engineering standpoint. Considering the age of the building and the number of earthquakes the area has suffered, it is amazing that the building is still standing. Some earthquake damage can be seen such as a leaning column in a photograph below.
Hagia Sofia
Arches
Central area
Carved stone arches
Central dome
Column leaning from earthquake
Front of interior
Hall
Mosaic revealed under painting
Stone panels
Virgin Mary mosaic