Baden-Baden is the most famous mineral water resort in Germany. In 1931, the town of Baden-Baden was officially given its double name, which is the short form for "Baden in Baden" (i.e., Baden in the state of Baden).
The German word Baden translates as "baths". Springs of Baden-Baden were known to the Romans, and foundation of the town refers to the emperor, Hadrian, with an inscription of somewhat doubtful authenticity. The bath-conscious Roman emperor, Caracalla, once came here to ease his arthritic aches. Baden was also known as Aurelia Aquensis, in honour of Aurelius Severus, during whose reign Baden would seem to have been well known. You can still find fragments of its ancient sculptures. In 1847, the well preserved remains of Roman vapour baths were discovered just below the New Castle.
There's a lot of interesting places in Baden-Baden. Upon arrival we visited the mineral water pavillion, also known as tourist information office. Baden-Baden is a quite confusing city, so we recommend that you buy a map. Then we signed up for a casino tour. Casino in Baden-Baden is the oldest and most famous in Germany. Marlene Dietrich called it "the most beautiful casino in the world." A lot of celebrities left their autographs in the guestbook. You can visit the casino with a guided tour in German before noon. Pre-visit the official site to check the column on the right for the dates on which the tours are not held.
After that we walked around the pedestrian city center and went to the Mount Merkur funicular by bus #204 (or 205). Every 15 minutes from 10 am to 10 pm you can go uphill and see the city from the 370 meters height.
Then by bus #204 we went to the Geroldsau waterfall (Geroldsau Malschbacher Straße bus stop). The waterfall itself is small, but we were just interested in a walk through the forest. From the bus stop we went down the Geroldsauerstrasse Street, and then along a forest path, following the signs.
By the same bus #204 we got back to the downtown, where we walked, and then went to the train station. Bus schedule in Baden-Baden and map of the stops can be found here.
We visited only a few interesting places in the city and will come here again. You can find a decription of all sights at the website and plan your stay. See here and here.
Here is a good map, which we took at the tourist information office.
Getting there: Trains of all types, including ICE, pass the train station in Baden-Baden. The road by regional train from Karlsruhe takes about 20 minutes, from Stuttgart 1.5 hours. There's about 4 km from the station to the city, so it makes sense to go by bus.