Afrasiyab is the eroded earthen mound where the original Samarkand stood, until Genghis Khan's army destroyed it in 1220. The city was one of the great trading hubs of the Silk Road, with walls, palaces, and reception halls covered in Sogdian wall paintings; after the Mongols, the survivors moved a few kilometres south and built the city you walk through today.
What remains is a 220-hectare archaeological park of low grassy mounds and exposed brickwork, easily walked in a couple of hours. Excavations continue and the views from the higher ridges over the modern city are excellent. The Afrasiyab Museum at the south edge displays the best finds. Combine with the Tomb of Daniel and the Ulugh Beg Observatory next door.