CASTIGLIONE OLONA, a village of Lombardy, Italy, in the province of Como, 27 m. N.E. of Milan by rail. Pop. (1921) 834 (commune) 2,168. The choir of the collegiate church, erected about 1428 by Cardinal Branda Castiglioni, contains fine frescoes by Masolino of Florence. There are other works by the same master in the baptistery. The tomb of the cardinal ) is good. The church of S. Sepolcro is also in the village.