Niksar, a regional center (pop. 29,000), lies 57km/35mi northeast of Tokat on the slopes above the Niksar valley. In Roman times it was known as Neocaesarea and also as the Pontic kings' famous fortress Cabeira. Mithradates VI Eupator had a hunting lodge here. The Byzantines and Ottomans transformed the castle into its present structure. The
remains stand above the lively old town on a rocky ledge. The castle complex consists of a medrese (1158) and a türbe. The single story medrese with a self-contained hall was badly damaged in the earthquakes of 1939 and 1942. It was in Niksar in 71 B.C. that Lucullus won an important victory over the Pontic rulers. Seven years later the fortress fell to Pompey.
The town's prosperity returned after 1071 when the Danishmends established their court here. The founder of the dynasty Melik Gazi is buried in the town. In the district of Bengiler stands a mausoleum with the remains of Bedrettin Sah, one of Kiliç Arslan II's generals.
Another interesting collection of tombstones contains that of a woman named Külah (1220), the Kirk Kizlar Türbesi with arabesque decorations and the Seljuk Akyapi Kümbeti which lies alongside the Melik Gazi Türbesi and dates from the 13th century Another Seljuk caravanserai (1224) can be found in the town. Niksar was the birthplace of Gregorius Thaumaturgos (212). To the church fathers he was known as Pontic Gregorius and became the first bishop of Neocaesarea. In Christian times the town was designated as a metropolis and in 314 it was the venue for a Christian Council.
Some 2km/1.75mi outside Niksar lie the Ayvas mineral water springs. The waters from this source are well known throughout Turkey and are said to be effective against kidney-, bladder- and gall-stones, arteriosclerosis and high blood pressure.