There were no bridges over the Golden Horn in Byzantine times. People traveled from one side to the other in boats. The site of the bridge said to have been built by Justinian in the 6th century is not known with certainty. In fact it is almost certain that this bridge was not over the Golden Horn.
It is possible that the bridge in question spanned the mouth of the Kâğıthane Creek at the point where it flowed into the Golden Horn. It is not known what the remains, thought to have been the supports of the bridge, seen in the Ayvansaray course by the French traveller Pierre Gilles of Albi (Gyllius) in the l6th century, were. It is indeed doubtful that they belonged to a bridge.
In 1453, when the city was being besieged by the Turks, Mehmet the Conqueror had a pontoon bridge built over the upper part of the Golden Horn. This bridge can be quite clearly seen in the miniatures in a travelogue by Bertrandan de la Broguiene, executed about two years after the conquest. For many years after the Ottoman conquest, people traveled from one bank to the other by boat. It was in 1836 that the two banks were linked for the first time by the Hayratiye Bridge, which lay between Unkapanı and Azapkapısı.
The first bridge between Eminönü and Karaköy, which was made of wood, was built in 1845. Both bridges were renewed a number of times over the years. The existence of the old bridges over the Golden Horn has been documented in engravings and photographs.
The bridge between Eminönü and Karaköy was built by the German MAN company in 1912. It was the fourth of its kind and has just stopped being used very recently. The fourth Unkapanı Bridge, also known as Atatürk Bridge, was constructed in 1939 by a French firm. The bridges over the Golden Horn are still said to be the world’s longest pontoon bridges.
However, pontoons are considered to hinder the flow of water from the Golden Horn into the Sea of Marmara and for this reason the new Galata bridge between Eminönü and Karaköy was built on piles.