Hpa'an is famous for its stand-alone limestone mountains with caves full of Buddhas but to see them you'll need to rent a tuk tuk and probably find a local guide to help explain them to you. The infrastructure is still mostly geared towards the local Burmese who use these caves as temples. We found a local guide who came to pick us up in his wonderfully ramshackle tuktuk and shuttled us out into the fields and to the limestone mountains where the caves are found. Mr Win was wonderful and here are his details - U Thein Win, tel: 09-49771213, ask for him at the Parami Motel.
The caves are a nice change of pace from the traditional temples and are a riot of colours and carvings. My favourite was one of the biggest caves which you could climb through and out onto a ledge on the other side of the limestone mountain.