The church of Saint Prokopios with the nickname "at the Turtle" was built in the 11th century, replacing an older church of the early byzantine time. It was enlarged by an outer narthex with three domes in the 14th century and became a mosque after 1453. When Pierre Gilles, the first european scholar who wrote a book about the city in the 16th century, asked local Greeks for its former name, they called it Saint Theodoros, thus confusing two military saints. Since then, several fruitless attempts have been made to identify it with one of the churches of Saint Theodoros known from the sources. The identification with Saint Prokopios appears much more plausible on topographical grounds.