What can you do with a 1 year old on vacation?

We are planning a family trip to Switzerland in May and it will be just before by son's first birthday. What are some things to do when you have a 1 year old? We will be going mostly to the Alps and Zurich and might spend a day or two in Germany and Lichtenstein. This is my first child so I'm not sure what fun activities are with a 1 year old in general. Any help would be appreciated.