There are two Caverns.

One - the original one where the Beatles actually played - there are all types of groups playing and it pretty much gives you the feeling of the 60's - definitely a must see. They only charge entrance on the weekend. All beatlemaniacs must see.

In front of it there is another (smaller) Cavern in front which has some original instruments from UB40, Paul McCartney, and Michael Jackson. This is free and you can often listen to some good but nice live musicians. A great atmosphere.

http://www.cavernclub.org/