 The construction of the moat started by digging the marshy land which was around the fort in all direction other than west (west of fort was Indian Ocean).But these works were demotivated by the size of it and the small amount of water in the marsh which was not enough to fill a lake.But a stream which flowed between Mount of Dematagoda and Mount of St. Bastian was discovered in this situation by Portuguese Captain Lopo de Brito, while he was chasing away another invasion lead by King Vijayabahu VII.