Pompeiopolis (Greek: Πομπηιούπολις) was a Roman city in ancient Paphlagonia, located near Taşköprü, Kastamonu Province in the Black Sea Region of Turkey. The exact location is 45 km north of Kastamonu and a short distance across the river from modern Taşköprü, in the valley of the Gökırmak (Roman name Amnias, or Amneus). The borders of Pompeiopolis reach the Küre mountains to the north, Ilgaz mountains to the south, Halys river to the east and Pınarbaşı valley to the west. The city's remains today consist of an acropolis, some rock-cut tombs, tumuli, a bridge and remains of houses with mosaic tile floors. It is believed that many more artifacts and remains can be uncovered if further archaeological excavation can be conducted at the Zımbıllı hills within the city boundaries.
Pompeiopolis was established together with Neoclaudiopolis as one of a number of cities founded by the Roman general and politician Pompey (Gnaeus Pompeius Magnus) and integrated into the new Roman double province of Bithynia-Pontus in the year 64 BC. It was later assigned by Mark Antony to the vassal princes of Paphlagonia, and in 6 BC, after the death of Deiotaros Philadelphos, the last king, Paphlagonia was re-integrated into the Roman Empire and placed under the governor of the province of Galatia. While the city flourished and grew during this period, it was the metropolis of Paphlagonia from the reign of Antoninus Pius until that of Gallienus, having a civic mint in the same period, as well. The city was called Sebaste for a short period of time during the patronship of Gnaeus Claudius Severus, Marcus Aurelius' son-in-law. Rare coins surviving from that era bear the inscriptions "Sebaste Metropolis of Paphlagonia". w Being a bishopric since the early 4th century at latest, Pompeiopolis received the title of autocephalus archdiocese at some time during the reign of Justinian I. Within the church province of Paphlagonia, Pompeiopolis always ranked immediately after Gangra, and above the other bishoprics.
It is currently believed that Pompeiopolis was deserted in the early 8th century AD after the attacks of the Arabs Muslim conquests and as a result of the defensive military reorganizations of the Byzantine emperors of the 8th century. This region was conquered by the invading Turks in the late 11th century. In the 10th/11th century, Pompeiopolis became a metropolitan see until the 14th century, when this diocese was suppressed. Among the fourteen known titular holders of the Christian diocese are Philadelphus at the First Council of Nicaea, Severus of Constantinople and Theodore of Constantinople.
Many of the artifacts that were revealed in the course of those excavations are currently being exhibited in the Museum of Archaeology of Kastamonu. Since 2006 the University of Munich (Germany) is conducting excavations on the archaeological site under the direction of professor Lâtife Summerer.