ordered the hollow to be flooded in order to complete the defences of the town and Edinburgh Castle. The loch was formed by creating an earthen dam to block the progress of the Tummel Burn, a stream that ran along the foot of the north side of the castle rock. The water level was controlled by a sluice in the dam which was at the foot of Halkerston's Wynd.

Because the Old Town was built on a steep ridge, it expanded on an east-west axis, eastwards