Can I do a VFR night sightseeing flight in Europe?
Yes you can file a flightplan with the same departure and destination. You generally do not need to include detailed routing, unless local rules require you to do so (but if you are planning to cross a country border, you probably need to include a point of crossing and estimated time). One thing to consider is that the EET in your flightplan should be accurate, since alerting service is based on that (if you don't arrive within a certain amount of minutes after your ETA, search and rescue efforts will be initiated). However, as long as you are contact with ATC while in the air, you can always just inform them of a revised ETA, and they can pass that on to your destination airfield.