from ten to seven towers

In the North-eastern region of Thessaloniki, a big fortress is situated called Heptapyrgion. The towers were built in the 4th century to enclose the medieval city, but its modern form is from the 14th century.
The byzantine name Heptapyrgion and later the ottoman name Yedi-koule both mean “fortress with seven towers”. In reality, this monument has ten towers. It’s believed that took the name after the fortress of Constantinopole (modern Istanbul). For one century (1890-1989), it ran like a prison, housed in new buildings that were constructed inside its walls. 
Nowadays, some spaces of the ex-prison are open to the public (Tue-Sun 08.30-17.00) with free entrance. In the surrounding area, you can find many restaurants, taverns and coffee-bars and of course, a breathless view of the city.