Mulhouse is not the most beautiful city of Alsace, but you can enjoy this place. It has a central position in the city. Its about only 10 minutes from the train station.
During the winter, the Christmas market takes place here. During the summer, you can buy ice cream in the street and many other products. This aera is also nice for shopping, specially during sales.
This is the historical center of Mulhouse : the church (protestant temple) is from 1528, the city hall was built in 1553 and plainted in 1699...
For the rest, you can go to the railway museum (avenue de Colmar) and the automobile museum (500 meters/1800 feets) from the "Avenue de Thann".
Enjoy !!!