Make sure you check the weather before making a trip to Merkur Mountain. We didn't and it was foggy and we couldn't see anything. I was bummed.
But... You take the train up the really steep mountain which is fun. There is a watch tower you can climb or ride the elevator to the top and see the landscape. There is a café/bar there that looked good. We didn't eat, but it looked good. There was a play area for the kids. They loved it. Brochures were in all languages. People were nice. I visited with my husband and young kids (5 and 2).