The Great Mosque was so nice. It was the most beautiful "tourist attraction" I went to while in Xi'an. DO NOT forget your camera you will want to take a million pictures and they will all be postcard beautiful!
It is only 12 Yuan (1.70 CAD) so if you are in Xi'an for a long period of time and you are staying close to the Mosque you can always go there for some peace and quiet. There were not very many tourists and it was so peaceful. Bring a book or your journal to write in. It was really nice and relaxing. To get there just take a taxi to the drum tower, go through the big tunnel. Once through you are in the Muslim Quarter of Xian. I would take a nice alley way to get there it is to your left once through the tunnel. You will see some tables and will notice it is a long alley. Keep going till you get to a point where you can make a turn. You will see a window where you can pay and the entrance. I can't remember if it says "The Great Mosque" in English but I don't think so. If these directions are confusing see "shopping"

When you are in Xi'an you really should walk or bike on the wall. If you don't know yet there is a huge wall that surrounds the city. I believe that you get on top from the "North Gate" Only!
I was tired by the time I climbed the stairs to get on top of the wall.
It takes about an hour (if you just walk) but I would take up to two hours because you will want to look over the wall and take pictures of the city from up there. It is really nice and worth the money. I believe it costed me 40 Yuan. (5.67 CAD) this is one of the more expensive tourist sites. Once you on the wall there are also some great art shops and vendors. Don't buy the paintings there though, you can get them cheaper in the muslim market.