Strasbourg (Strassburg in German) is a city for a short visit for a couple of days or for christmas market in Advent. It is not very suitable for a base in Alsace: it takes quite a long time to get to any interesting point – either to the north or to the south. True, there are many hotels in the city, and this makes it very likely that this is where you will stay.
A significant part of the old city is on the UNESCO list, including the most famous landmark – Strasbourg Cathedral.