It includes 58 comuni (municipalities), the most important today being Vigevano and Mortara; the name however derives from its ancient capital Lomello.
Among his many works: a Madonna for the Sanctuary of Bozzolo (near Garlasco); Santi Maurizio e Lazzaro for the chapel of the Hospital of Sanzo; a Christ among the Children for the asylum of infants founded by signor Niccola Traversi in Lomellina; The Delirium of Ermengarda from the play Adelchi by Alessandro Manzoni; Death of Count Rosso; A Prayer at Subiaco.
Near Cerano, it splits into two different streams: the first joins the Ticino River, while the second flows through the Lomellina (province of Pavia) until it merges with the Po River.