Been there, done that!

I don't personally like this expression. I find it it often intended to be very flip (impertinant, disrespectful) and far too nonchalant and worldly-wise in a contrived way for my taste. The idea is that whatever you're talking about (not necessarily a place) no longer holds any interest for you. You've finished with it and don't care to deal with or think about it anymore.

It can be made more emphatic by adding "got the t-shirt" to the end.

It's generally considered an American expression, although this may not be entirely true. Some people also use it to simply mean that they've done something, with no idea of boredom or lack of sustained interest. This is especially true when speaking about travel.