SINIGAGLIA, a town of the Papal States, in the legation of Urbino, at the mouth of the Misa, in the Adriatic, 16 miles W.N.W. of Ancona. It is regularly, but not very strongly, fortified, with ramparts, bastions, and a citadel. The buildings, which are almost all modern, are generally good, and the streets broad, straight, and regular. There are a cathedral in the Corinthian style, in the form of a Greek cross, several convents, a mint, a theatre, and a small harbour. Sinigaglia is celebrated for its annual fair, in the end of July and beginning of August. This has been established for several centuries, and attracts great crowds from all parts of Italy. The town occupies the site of the ancient Sena, surnamed Gallica, to distinguish it from the place of the same name, now Siena, in Etruria. It is infamous in history for the treacherous murder, in 1502, by Cæsar Borgia, of several chiefs who were in alliance with him. Pop. 9000.