Yedikule Fortress, famous for its dungeons

The construction of Yedikule Fortress, famous for its dungeons, took place between 413 and 439. It was commissioned by the Eastern Roman Emperor 2nd Theodosius, who valued architecture. Initially, a victory arch was built with the purpose of being used for the entrance to the city upon returning from wars. During the reign of 3rd Theodosius, it was converted into a gate as part of the construction of sea walls to defend against attacks from the Sea of Marmara, and it became known as the Golden Gate.

For centuries, the Golden Gate served the function of welcoming victorious emperors returning from wars. Ceremonies were held at this gate for emperors who returned from victorious battles, and they entered the city accompanied by processions.

The main ceremonial gate, known as "Porta Aurea" during the Eastern Roman period and "Yedikule Gate" during the Ottoman period, was one of the most important structures of the land walls. The Via Egnatia, an intercity road connecting Istanbul to Rome, started from this gate and, after passing through it, connected to the main street in the city, known as the Mese in Eastern Roman times and the Divan Yolu in the Ottoman period. This significant intercity route terminated in the Augusteion square in front of the Hagia Sophia, which is now known as Sultanahmet Square.

Throughout its history, many famous individuals were imprisoned in the Yedikule Dungeons, including:

- Çandarlı Halil Pasha and his sons

- David Komnenos, the Trabzon Greek Emperor, and his sons

- The last Abbasid Caliph, IV. Mutawakkil

- Crimean Khan Mehmet Giray

- Stephanus Alberti

- Commander of the Corinth Garrison, Julius Andrea Virasina

- Grand Vizier Kara Davud Pasha

- French Consul Jean de la Haye

- Chief Architect Kasım Ağa

- Deli Hüseyin Pasha, the Conqueror of Crete

- Armenian Patriarch of Istanbul, Avedik

- Wallachian Prince Constantin Brâncoveanu

- Russian Ambassador Count Tolstoy

- Russian Ambassador Aleksi Oberskov.

2nd Osman (also known as Young Osman) was an Ottoman Sultan who was killed by the Janissaries in these dungeons.

On May 19, 1622, rebels entered the palace and proclaimed Sultan Mustafa I. Some of their demands were met, but this had no lasting effect. In response, Sultan Osman II (2nd Osman) sought refuge with Janissary Ali Ağa and asked him to persuade the Janissaries. However, Ali Ağa's attempt to convince the Janissaries was prevented, and he was attacked and killed with a sword. At the same time, one of the rebels who had captured Sultan Osman squeezed his hips and insulted him. Sultan Osman was eventually taken to the Yedikule Dungeons, where he was imprisoned. He resisted those who wanted to kill him and was ultimately strangled with a noose around his neck.