The Isa Bey Mosque is one of the most accurate examples of Seljuk architecture. It is located in Ephesus under the Cathedral of St. John. It was built by the Syrian architect Ali bin Mshaimish of Damascus between 1374 and 1375 AD. The mosque was designed asymmetrically in contrast to the traditional style. The location of the windows, doors and domes was not intentionally matched. There is an Islamic inscription adorning the entrance. The columns inside the prayer house are from earlier ruins in Ephesus, which forms an interesting contrast with the mosque. The domes are decorated with a blue turquoise decoration that reveals the characteristics of the Ottoman style.