Mulkirigala Rock Monastery

This one is situated in Sri Lanka's slightly better known Tangalle.  Though we bet you're surprised to find any religious site on this list, this is the kind no one should miss. Besides, it's not even close to a main tourist attraction though everyone who does choose to visit never regrets it. 

Within the caves, which you must trek up to, exists some of the most stunning Buddhist artwork and architecture you will ever lay your eyes upon. Plus the entire scenic view you'll be rewarded with upon reaching the top of these hills are good enough reason to go.