Saint Gregory of Nyssa was a church and monastery of Trabzon. It's believed the church was built around 1280-1297 by the wife of John III, Emperor of Trabzon. After 1665, St Gregory became the cathedral of the city of Trabzon. The church is dedicated to Saint Gregory of Nyssa (c. 330-395), a Christian bishop and saint. Nyssa (current day Nevşehir) is a city located in Cappadocia. In 1863 the Metropolitan Constantius of Trabzon rebuilt the church.
In 1930 the church was dynamited to make way for the City Club.