The site of Nyssa has been identified as near the modern town of Harmandalı, Ortaköy district, Aksaray province, in south-central Turkey. The archaeological site consists of two tells, named Büyükkale (big castle) and Küçükkale (little castle), located 2 km to the north of Harmandalı.
Another proposed location associates it with the modern city of Nevşehir, but modern scholarship has cast serious doubt on this.
William Smith's Dictionary of Greek and Roman Geography placed the town at a village, not otherwise mentioned, called Nirse or Nissa and said that it was anciently in a district called Muriane, not far from the river Halys.
The Eastern Orthodox Church has continued to appoint titular bishops of Nyssa even after the town and its Christian community ceased to exist. In practice, these titular bishops held jurisdiction over Orthodox Christian communities located elsewhere. Since 2012, the title "Bishop of Nyssa" is held by the bishop of the American Carpatho-Russian Orthodox Diocese.
In the 18th century, the Roman Catholic Church also began appointing titular bishops of Nyssa (Latin: Nissa).
The Catholic see is currently vacant, having had the following incumbents:
Francesco Giacci (1900.09.26 – 1904.07.03) as Auxiliary Bishop of Diocese of Frascati (Italy) (1900.09.26 – 1904.07.03); next Bishop of Marsi (Italy) (1904.07.03 – 1909.04.29), emeritate as Titular Bishop of Philomelium (1909.04.29 – death 1929.02.20)
Giovanni Battista Arista, Oratorians (C.O.) (1904.11.14 – 1907.11.04) as Auxiliary Bishop of Diocese of Acireale (Italy) (1904.11.14 – 1907.11.04); next succeeded as Bishop of Acireale (1907.11.04 – death 1920.09.27)
Laureano Vérez de Acevedo (Spaniard), Jesuit Order (S.J.) (1908.08.22 – death 1920.01.31), no actual prelature
Jules-Alexandre Cusin (1920.03.08 – 1929.05.29) as Coadjutor Bishop of Diocese of Mende (France) (1920.03.08 – 1929.05.29); next succeeded as Bishop of Mende (1929.05.29 – 1937.06.05)
Adriano Bernareggi (1931.12.16 – 1936.04.14) as Coadjutor Bishop of Bergamo (Italy) (1931.12.16 – 1936.04.14); next succeeded as Bishop of Bergamo (1936.04.14 – 1953.06.28), emeritate ('promoted') as Archbishop ad personam (1953 – death 1953.06.28)
Biagio Budelacci (1936.06.18 – death 1973.08.27) as Auxiliary Bishop of Diocese of Frascati (Italy) (1936.06.18 – 1962) and on emeritate