The terracotta and Mausoleum of Emperor Qin Shi Huang is situated together. They are a little far away from the city proper of Xian. If you rent a taxi, it may cost 200rmb to get there. In the east square of the railway station, there are tourist bus line to the spot. The city wall surrounds the inner city of Xi'an. In the center, there are the Bell Tower. In the northwest of the Bell Tower, It is the Drum Tower. Behind the Drum Tower, it is a famous snack street of Muslim food. The big Wild Goose Pagoda and grand music fountain on the square north of the pagoda. Just a few minutes walk from the sqaure, there is the provincial history museum of Shaanxi, which is also a good place worth visiting.
Hope it helps.