Leonardo was in Vigevano between 1493 and 1494. During his stay, he visited the rural area of Vigevano and Lomellina, where reclaiming and drainage, irrigation, and hydraulic works were bustling by order of Ludovico Il Moro.
Leonardo, who was superintendent at the root canal treatment works in 1490 in Milan, probably used all his agricultural and water culture here. Indeed with an accurate study of water energy and a laboratory (in Vigevano city), he planned new ways for rice irrigation.
He described an ingenious project for reclaiming marshy lands, to be executed using water. “Ladder at Vigevano, below La Sforzesca: 130 large stairs, 1/4 braccio high and 1/2 braccio wide, and the water falls over these and does not consume anything in its last percussion. And so much earth will come down along this ladder that you can [use that to] dry out a marsh, that is, fill it in, and meadowlands can be made even from very deep marshes.” (english translation of Codex Leicester, f. 32 r.).
The “ladder” at Vigevano was initially used for reclaiming land and subsequently for bearing water to an irrigated meadow on a steep slope: it was a construction of great interest in terms of the techniques of reclaiming and irrigation. Leonardo observed in general that “marshes will be filled in with earth when turbid rivers are conducted into them.