Refectory, Medamaluwa Monastery, Mihintale
These huge stone troughs were supposedly filled with food (assumed to be rice and gruel) for the monk's meals. The trough on the left is a simple receptacle, but the trough on the right has two separate basins; the main basin is long and rectangular, with a sloped and stepped bottom; the second basin has a circular cross-section and abuts the end of the first. It is not clear to me how it was used in practice, but I suspect that it may have had something to do with laundry rather than food.
The size of these food troughs, if they are indeed food troughs, indicates that the monastery supported thousands of monks. The output of several villages would be required to feed this number of people. Personally I think they were laundry troughs instead.