Visible overhead are two travertine corbels protruding from the masonry, which served to support a necessarium, a latrine for the needs of the soldiers stationed in the tower or on guard duty along the covered walkway. These structures were in fact located outside the walls at the point of passage between the tower and the walkway, generally occupied by a small room (prothyrum) faced towards the enemy and covered with a vault, which was also useful for diverting rainwater. Almost all of the necessaria (recorded in a 9th-century document, the anonymous Eisiedeln manuscript) have since collapsed, while at various points along the walls, the brackets that supported them are still in place.
