Sultanahmet Square was a racetrack. In January 532, rival fans who hated each other stood in it chanting the same word. An emperor thought about running.
Septimius Severus built the hippodrome in AD 203; Constantine rebuilt it after 324. Chariot teams raced in colours tied to political factions. Two mattered: Blues and Greens.
Then 532. Taxes, two hated ministers, a lost battle at Callinicum, violent fan gangs. On 10 January a Blue and a Green condemned for murder survived their hanging when the scaffold broke, and were taken into the church of St Laurence.
On the 13th Justinian called a race and commuted the sentences. It didn't work. The crowd insulted him, then the rival fans chanted together: "Nika". Win. And they went for the palace.
Fires took much of the city; the old Hagia Sophia burned on 13–14 January. The ministers were sacked. The rioters crowned a rival, Hypatius.
Procopius says Justinian considered flight, and gives Theodora a speech: royalty, she says, makes a fine burial shroud. Did she say it? Some scholars hear palace debate dressed up; some think Procopius invented it. Her life is its own story.
Then Belisarius and Mundus led troops into the Hippodrome, and Mundus's men killed without picking targets. Procopius counts about 30,000 dead; another chronicler says over 80,000. Hypatius was executed.
On 23 February 532 Justinian laid the foundation of a new Hagia Sophia on the ashes of the old. A riot gave Istanbul its Hagia Sophia.
Walk Sultanahmet Square at first light; it's public, no ticket. Pace the line from the German Fountain to the obelisks, which stand on the old spine; the track ran about 2 m lower, so look down into the pits. The crowd crosses to the Blue Mosque; you stand by the Serpent Column and read the line of monuments.
