Yoros Castle (Turkish: Yoros Kalesi) is a ruined castle at the confluence of the Bosphorus and the Black Sea, a highly strategic location. It is just north of a small fishing village called Anadolu Kavağı, on Macar Bay (Asian shore of the Bosphorus). The fortress is also commonly referred to as the Genoese Castle, as it was built on their initiative around 1350. The construction method, however, was typical Byzantine, using alternating layers of stone and brick.

Regarding Genoa and the Byzantine Empire:
In 1169 already, the Byzantine emperor Manuel I signed a treaty with Genoa, in order to offset the domination of Venice in Mideterranean trade. One century later, Genoa assisted Michael VIII during his reconquest of Constantinopel upon the Latins. As a result, the Genoese obtained the control over Galata (on the northern side of the Golden Horn) as well as the vast majority (87 %) of the custom duties paid on the Bosphorus. The latter mined the Byzantine economy so badly (by increasing the prices, without any profit for the Byzantine state), that in 1348 John VI Kantakouzenos decided to lower all taxes drastically. The Genoese riposted by destroying the newly built Byzantine fleet (1349). In the aftermath of this conflict, the Genoese had the Yoros Castle built, to strengthen their position, chiefly against the Venetians, who were the Byzantines’ ally at the time, as well as Genoa’s mortal enemies. By 1354 the Genuese position on the Bosphorus was restored, as they organised the palace revolution that installed Andronikos IV Palaiologos on the Byzantine throne.
When the Ottomans besieged Constantinopel in 1453, the only external help the powerless Byzantine empire got, came from the Genoese captain Giustiniani and his 700 soldiers.

Correspondent: J.M.Criel, Antwerpen.
Sources: ‘Guides Bleus: Turquie’ – Edition 1986 & ‘La Civilisation Byzantine’ – André Guillou, Paris 1990.