Yedikule Dungeons, also known as Yedikule Fortress, is a historic structure with a past spanning both Byzantine and Ottoman eras. Originally built as the Golden Gate under Emperor Theodosius I, it later became a fortress and infamous prison where high-profile figures, including Sultan Osman II, were imprisoned and executed. With its towering walls, dungeon cells, and old prisoner inscriptions, Yedikule offers visitors a glimpse into Istanbul’s darker history while also providing panoramic views from its ramparts.