Beijing shows you the last dynasties. Xi'an shows you the first ones. The Zhou, Qin, Han, Sui and Tang all ruled from here or next door, and under the Tang this city was Chang'an, the capital at the eastern end of the Silk Road. The name Xi'an (western peace) only dates to 1369, when the Ming gave it. The Terracotta Army is the reason most people fly in, and it earns it, but it guards the tomb of one emperor, and there are more than a dozen dynasties of history under this plain.
It's also a living city of about 13 million people, ringed by a Ming wall you can ride around on a bike. Inside it, the Hui Muslim community has lived around the Drum Tower for more than a thousand years, and the food follows: wheat instead of rice, noodles the width of a belt, lamb, cumin, vinegar and chili oil. Five days works because the headline sights are spread out. The Terracotta Army is a full day with Huaqing Palace, Mount Hua is a full day of hiking, and three days are left for the city itself, the part people regret skipping.
Day one is the old city inside the wall: towers, mosque, food and a bike ride. Day two is a day trip to Lintong for the Terracotta Army and Huaqing Palace. Day three is southern Xi'an, with the Shaanxi History Museum and the Big Wild Goose Pagoda. Day four is the second day trip, Mount Hua by train, and day five is the Stele Forest, the Little Wild Goose Pagoda and the Tang palace ruins. Start on a Tuesday if you can: it keeps the museums clear of Monday closures, puts the Terracotta Army and Mount Hua on weekdays when the crowds are thinner, and leaves Saturday for the museums with reservations. Read the tips before you book flights, because entry rules, paying and the internet work differently here than almost anywhere else, and there's more in our China guide.