Taking a walking tour is a fun and active way to experience history, second only to reenacting a Civil War battle or accelerating beyond 87 miles per hour in a DeLorean. Stroll your way though yesteryear with today's Groupon: for $28, you get an armory and adult-film set tour for two at SF Armory (up to a $65.28 value).

Patrons must be 18 years or older.

Completed in 1914, the 220,000-square-foot San Francisco Armory has a storied history, hosting the National Guard until the early 1970s, remaining vacant for three decades, and being bought and refurbished for adult-film sets by Peter Acworth, owner of Kink.com. Earning a feature on ABC 7 last April, Acworth's team helms 90-minute tours through the armory's five expansive floors as they sling an innovative blend of historical and risqué trivia, much like the Chancellor of the Smithsonian Institute after hours. Guests can amble through the preserved shooting range before following the subterranean burbles of Mission Creek through the basement. A menagerie of ornate and functional fetish film sets detailed by the San Francisco Examiner includes a plush lounge and dungeon environments, complete with props forged in an on-site metal shop. Depending on their timing, groups may also glimpse a live filming in progress, though the staff requests that patrons refrain from ogling the working boom mikes.

Click here for tour details, dates and times.