Castelfidardo (Marchigiano: Castello) is a town and comune in the province of Ancona, in the Marche region of central-eastern Italy.

It is remembered for a Piedmontese victory over an army composed of foreign volunteers defending the Papal States, on September 18, 1860.

It houses artifacts and documents of the period, including around 130 loans from private collections or other museums.

In addition, Castelfidardo is home to a number of Renaissance-era buildings, including 'il Palombarone` a 1580 construction which underwent extensive renovations in the early 21st century.

Currently, it plays in Italy's Serie D after the promotion from national play-off in the Eccellenza in the 2013–14 season.