Two of the sites which help define Xi'an are the Bell and Drum Towers set fairly centrally within the city walls. Built in 1384 and 1380 (respectively) during the Ming Dynasty, the towers are about 40 meters tall and were used to tell the times of day. At dawn the bells would be struck and at sundown the drums would beat.
Now the towers house museums displaying bells and drums, other musical instruments from the Ming and Tang dynasties, textiles, and weapons. There are also (big surprise) over prices gift shops. One of the cool things about getting around in Xi'an are the subways. Not subways as in a metro train, but walkways underground to help pedestrians negotiate the city without worrying about dying in the insane traffic. These subways are lines with shops and separate pathways lead to each of the towers, making them easy to visit.
Seveal times every day there are performances at each tower. The bell tower features a number of different instruments as well as the bells and a dancer.
And the drum tower has a drum performance.
Like many of the buildings in Xi'an, the towers are also very pretty at night.