I visited in Bethlehem in January 2011 and of course the main site there is the Church of the Nativity. When I entered the church (through very small door) there was service still going and the priests (or monks) were singing and incense was smelling strongly. Because the priests were inside of the Grotto of the Nativity their singing was echoing mysteriously around the church. Very mystic atmosphere. After the priests left somewhere through a secret door I went to see the grotto myself. Smell of incense was very strong and I had hard time breathing. I watched some time how people kissed the spot where Jesus was born and then walked around the church complex. When big Russian tourist group arrived I decided to leave the church.

As this is the most holiest place in Christianity I think it deserved the World Heritage Site status. The Church of the Nativity itself isn't really spectacular looking and also inside it's quite simple but the history is the thing that matters here.