First go to visit this place and than the Terracotta warriors. I recommend you to to do as I mentioned, otherwise you could be really disappointed. This place is as far as Terracotta warriors from the city center and it is actually a big underground museum. IT could be interesting if you have a passion for this kind of thing like tons of small object and small archeological treasure. Honestly this is definitely not my kind of place, but it is still interesting to take a look around.