Quotation from: The Notebooks of Leonardo Da Vinci
Written by: Leonardo da Vinci
_III. Castles and Villas.
A. Castles.
Pl. LXXX, No. 1 (P. V. fol. 39b; No. d'ordre 2282). The fortified
place here represented is said by Vallardi to be the_ "castello" _at
Milan, but without any satisfactory reason. The high tower behind
the_ "rivellino" _ravelin--seems to be intended as a watch-tower.
Pl. LXXX, No. 2 (MS. B, 23b). A similarly constructed tower probably
intended for the same use.