About a quarter of a mile inland from the Marmara Sea along the land walls is the Golden Gate entrance to the Byzantine city, a triumphal arch built by Theodosius. The arch predates the construction of the famed Theodosian walls and was used as a ceremonial entrance and exit to the city still for the most part confined to the boundaries set by Constantine's earlier defensive walls. From here, the main road, or "Mese," led directly through the center of the city, to the Milion Stone and Ayasofya. Theodosius later incorporated the gate into the construction of his defensive walls. Nearly a thousand years (and several earthquakes later) in 1457, Mehmet the Conqueror took advantage of the two towers flanking the Golden Gate, added an additional five towers, and enclosed them within a new defensive fortress. But the fort was never called to battle and served instead as the imperial treasury and a political prison for the likes of Mahmut Pasa, the Conqueror's Grand Vizier, and the deposed Mamluk caliph. Some unsavory incidents happened here too: When Sultan Osman II tried to reform the Janissaries in 1622, he was thrown in prison and then killed, and his head was tossed into what is now known as the "bloody well" in the center of the garden. Inside the Zindan Kulesi (Inscription Tower), some of the scrapings etched into the stone by the prisoners are still visible. The wooden scaffolding is what remains of the prisoners' cells. Steep and narrow stone stairways provide access to the top of the battlements, where you can breathe deeply the salty sea air and contemplate some of the finest views of the city. The stairway on the eastern curtain wall (to the right of the entrance) has one lone banister; ascend and descend with care.