Vacation destinations! (Frankfurt)

Hey Everyone,
I have a week or so off in February that I would like to spend somewhere really fun and interesting. I do have a limited budget, so going skiing for the week in the Alps or flying to Istanbul are out. I will have already been to France and Ireland, so I would prefer somewhere new. A good night life, rich culture and historical landmarks are preferable. Any suggestions? I'm really open to anything.
Thank you,
Sarah