Old town of Trebinje was formed because Turks needed organization of their territories in Herzegovina due to great changes in wars with the Holy league (1683-1699) – the fall of Herceg Novi and Risan under the rule of Republic of Venice.

It was built on the right bank of Trebišnjica, above the deepest part of the river – so called Ban-vir (vortex), named after a legend in which a ban (ruler) drowned in the vortex.

The most important person for the development of the Old town as a fort is Osman Pasha, founder of the Resulbegović family. He started the construction in 1714 but it was interrupted for a short time by the war with Venice. Builders were brought from Dubrovnik, and work force was from local area – Ljubinje, Cernica and Nikšić. During the next year a hendek (canal) was dug around it, which was connected to Trebišnjica. During Osman’s reign, Sultan Ahmed and Osman-pasha mosques were built, together with Sahat-kula (clock tower), which is still resistant to the many years that have passed.

Old town ‘Kastel’ was initially triangle-shaped and it became rounded over time. Its final shape, with all towers, canals and ramparts, was formed in the first four decades of 18^th century.

In front of the entry gate (today’s tunnel) there was a draw-bridge that was leading across the canal. The canal was later filled and levelled due to a possibility of epidemic disease, as advised by doctor Levi. (1932)