The remarkable name “Yeralti” literally translates as “underground.” This small mosque is housed within the remains of an ancient Byzantine fortress that once guarded the Golden Horn bay. In the tower that stood on this spot, the end of a massive metal chain was fastened; it closed off the entrance to the inlet and made it possible to control the passage of ships. At present, neither the tower itself nor the chain remains here. However, fragments of the barrier that have survived to this day can be found in the Istanbul Archaeological Museum.
At first glance, the choice of location for founding the mosque may seem strange, but in fact it is explained quite simply. In the underground chambers of the fortress, the remains of the Muslim saints Abu Sufyan and Amiri Wahibi were discovered; they died during the siege of Constantinople. A mausoleum was first built on the site where the relics were found, and then, in the middle of the 18th century, Yeralti Mosque was opened. Its low stone vault rests on 54 massive supports, and the tombs of the revered saints stand next to the niche in the south-west corner of the mosque.
