Contact Dutch Photo Trek . . . Your name . . Email address We’ll never share your email with anyone else. Confirm email address . Subject . . What whould you like to ask us? . . . . Send your messageorCancel The festival is held annually since 1863, and commemorates the 1573–1574 Siege of Leiden. 3 October is an official city holiday, with a variety of festivities, as these photographs reflect. Return .