This plaque was erected 500 years ago by Lodovico Sforza, commemorating the integration of the canal system. Leonardo is not credited on the plaque, but his design enhancements may have appeared on the gates rebuilt at this time.
Until about 1930, this structure was located to the side of the Viarenna lock. The marble used to build the Duomo passed through this lock on barges.
This lock at Viarenna, and the other at Incoronata, formed the two linchpins of the canal system.