Well Heidelberg has a big and well known university and therefore lots of students anyway, so I think it´s perfect for your purpose. You can have a great time here, in the evening the streets, riverside and lots of bars are full of students (not all drunk, but well...). And of course it´s quite pretty and you could do some "culture" (castle, old streets and buildings, museum) if you like those things.
Only bad point is that it´s a bit expensive to get a decent room. There are lots of students sharing a flat, but you should be early with searching a room.
Well if you really decide to stay here I could surely have a look for you.
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