Hello professor are you going to be anothe Senarath P.. like what he did on Thewatha paliya...Mange mole aulunalu neda anthima kale...budu darmaya sathyai...loketa atha kiyana pls..wandala kiyanam...rata goda gana atha kiyana...
My question is how water got filled there. If, as Roshan says, there was a roof or something to cover it, then it can not be rain water. My thinking is there must have been a water spout through a cavity in the Sigiriya rock itself. This sort of thing is possible due to our country is being situated below the earth's geoid. Even now we know we are some 80 meters below. Perhaps thousand of years ago it would have been several hundred meters and water would have gushed out due to low pressure. The same goes to Hortain plains where 'Adi man' or Adam may have lived. May be you can take my last sentence (not the whole thing as the earth is evolving continuously going through various phases) with a pinch of salt!.