Stand in Sultanahmet Square and you're standing on a racetrack. The Hippodrome of Constantinople is about two metres under your feet.
The historic peninsula is where Istanbul keeps its biggest names: Hagia Sophia, Topkapı, the Blue Mosque, Süleymaniye. UNESCO listed it in 1985 as one place, in four parts.
The museum isn't laid out side by side. It's stacked.
In 330, Constantine refounded Byzantium as Constantinople and planned a palace between the Hippodrome and the church. The Hippodrome was older, begun in 203 under Septimius Severus, with seats for about 100,000.
In 532 its crowds rioted and burned the second Hagia Sophia. Justinian built the one you see, 532 to 537.
Then 1453. The Ottomans built their capital on top of the old one. The emperors' Great Palace? Less than a quarter has been excavated, because most of it lies under the Blue Mosque and its neighbours.
So the square is a lid. The track's outline is traced in the paving. The Egyptian obelisk standing on it arrived in 390. Also in the square: the base of a Serpent Column from Delphi, 5th century BC; a walled obelisk from the 900s; a German fountain from 1900. Four eras in one square.
Is it a good base? In our 947-post Reddit set, Sultanahmet is the area mentioned most in the 142 posts about where to stay. Sleep here, and walk.
Come early on a weekday, by T1 tram to Sultanahmet or Marmaray to Sirkeci. Read the square first: the paving, the obelisk, the Serpent Column's base. Then leave the postcard cluster for the Süleymaniye hill and Zeyrek, where Sinan's mosque and a Byzantine monastery church stand a walk apart. Both are working mosques; check visiting times.
