The causeway entrance to Rosslyn Castle.

Frederick J. Pohl in his book "Prince Henry Sinclair - His Expedition to the New World in 1398" states: The castle "was also cleverly shielded by the one-hundred-yard-long embankment or causeway that, in orthodox defensive pattern, led out from the steep side of the valley to in front of the castle, where it made a short right-angled turn close to an arched bridge eighty feet above the bed of the stream below...Only a few attackers could be on the causeway near enough to attack the castle, and, since they carried their shields on their left arms, their unshielded right sides would be exposed to bowshots from the castle."