FILM: Delight in some yuletide noir classics at Castro Theatre's 2nd annual Noir City XMas 2011, featuring a double feature screening of Lady on a Train and Christmas Holiday. Additionally, the full schedule for the 10th anniversary edition of the Castro's Noir City X, which happens January 20-29, 2012, will be revealed. (7:30 to 11 p.m., Castro Theatre, 429 Castro Street)

ART: For their new installation, hidden in sight, Southern Exposure’s Youth Advisory Board (YAB) documented an anthropological survey of a secret society, in which they created both fact and fiction in their exploration, developing the secret society itself by determining its language, customs, codes, and characters, then setting up their own office to research these creations, the “Bureau of Hidden Insight.” (6 to 8 p.m., Southern Exposure, 3030 20th Street)

SCIENCE: Discovery Street Tours presents The Science of (Holiday) Light Walking Tour, which explores the city's most spectacular light displays along San Francisco stairways, side streets, and scenic vistas. The tour also features experiments with color mixing and animation, along with a history of holiday lights and seasonal treats. (6:30 p.m., Dolores Park, NW Corner of 20th and Church Streets)