I went to Kokino yesterday and was surprised to find this app existed before my trip. It does what it says on the tin and does it well. The audio guide has all the basic info on Kokino I was looking for and the length of the guide is just right for a leisurely walk through the site. It also has a map of the observatory that is handy for finding your way around and figuring out what's what. The written stories are a nice extra and something to do on the ride back.
Travel guide with audio sightseeing tours for 900 cities around the world!
Official guide for Hamburg - 1,500 POIs, tours, audioguides, shipfinder and more