You can use the iPhone as a map, even when you have no cell service. This is a trick I used abroad when I was going to a new country and knew I wouldn’t have a new SIM card before I needed to get somewhere. The trick is, you have to preload the maps.
The easiest way to do this is to pre-plan your route before you set off. From the train station or airport to your destination. Then you can scroll around a bit and download those maps. I usually like to zoom in or out just a bit and try and load as much of the map area as I can to help me out. I wouldn’t use this as my sole means of getting to where I’m going, but it’s pretty handy in a pinch!
When I get to where I’m going I can then access those maps even without a SIM card in the phone. This trick works even if you turn the phone off and back on and it should survive playing music and things. But don’t load other places in the map – you might lose some of the data you need. Also, the GPS is kind of spotty some places in Europe, and without Internet connectivity you can’t use the wifi or cell tower location services.