Upvote:0
You will find plenty of small unpaved roads and hiking trails in Central Europe. OpenStreetMap as suggested by Gilles is one possibility, the other are excellent maps (what do you need are so-called topographic maps).
You can acquire them in any bigger town in cartographic shops, there are also often maps given by the tourist information (hiking trails, biking trails) which can also give you the address of map shops.
If you are in hiking for a specific, small town, you can use 1:20 000 (you will see practically every doghouse), for hiking I suggest 1:50 000 which is also used by the German army and for a good overview over an area or an area with sparse infrastructure 1:100 000.
Upvote:5
OpenStreetMap is pretty complete in Europe (at least in the parts I'm familiar with), even when it comes to footpaths. It can be downloaded freely (there are smartphone apps to download the data and browse the map offline).
However, as an aid to hiking, it's lacks critical information for many locations. In particular, there's no elevation. There's no indication of which trails may be impracticable due to flooding or snow, of where and when there are risks of flash floods or avalanches, etc. If you're hiking or cycling in a region with no natural risk and not too many mountains, it's fine.
Most countries have some kind of national map agency which publishes good maps for hiking. But they are usually not free, and the cost to obtain sufficiently detailed maps for all of Europe would be prohibitive.