Dambulla
The cave temple, and the usual base for both the Cultural Triangle and a retreat week.
Dambulla’s cave temple is the certain cultural stop: painted ceilings, a short climb, and a visit that is done properly in a couple of hours. It is also the practical place to sleep if the next morning is Sigiriya or Polonnaruwa.
The Ayurveda sample uses a retreat in this country for seven nights, at Amuna, before anyone drives on to Kandy. If treatment is the point, do not plan the cave temple in the middle of the daily therapies. See it on the way in or on the way out.