I am unfortunately going to an unexpected trip to Oldenburg, Germany for 6 weeks. I have a question - what interesting can you visit during the weekends in cities near Oldenburg ? I'm just trying to be at the hotel as short as possible :-)
Oldenburg itself is not really a tourist sensation:-) However, if you have a car you can visit Hamburg in less than 2 hours and it's worth a weekend: a big port city with lots to see - for example the Reeperbahn:-)
About 3 hours drive and you are in Amsterdam, Holland - one the most beautiful cities in Europe, well worth a visit. Please notice that you will be searched when you return to Germany if you have a Slovakian car:-) They will assume you are smuggling drugs!
You can come visit me - I am about 4,5 hours away with a car. I show you my city and we can spend some time dicussing/listening to/watching Queen :-) Just email me with dates of your trip.
There are numerous interesting places throughout Germany. Considering where you're going, you might like to check the wikipedia pages on a number of cities in Nordrhein-Westfalen: link
There's bound to be something you like, and it's all relatively near by.