Kemeraltı is a historical market (bazaar) district of İzmir, Turkey. It was originally formed around the street surrounding the shallow inner bay of the city, which was filled in due course during the 17th century, availing the bazaar to be extended to a wider area. The street, that traces a wide curve and called today as Anafartalar Street (Caddesi), and known historically as the Street of the Mevlevis, in reference to the presence of a "dergah" (a building designed for gatherings of a Sufi brotherhood) situated by the street, constitutes the principal axis of Kemeraltı. The district covers a vast area extending from the level of the Agora of Smyrna (the quarters of Namazgah, Mezarlıkbaşı and İkiçeşmelik), to the seashore along the Konak Square. It remains one of the liveliest parts of İzmir.

The first step that paved the way for the emergence of the present-day Kemeraltı area was the building in 1592 of Hisar Mosque. It is the oldest and one of the most significant Ottoman landmarks in İzmir, although built by Aydınoğlu Yakup Bey, a descendant of the dynasty that had founded the Beylik of the same name (Aydinids) which had controlled İzmir prior to the Ottoman conquest. The name of the mosque, which means "fortress", makes reference to the Genoese castle of "San Pietro", previously called Neon Kastron in Byzantine times, part of which used to stand on the same location and which gradually disappeared in whole with the construction of new buildings on its spot. The final remains of the castle were cleared up during the construction of new port installations between 1867-1876.