It's baaaaaack. This Saturday, don't be alarmed if you pass groups of frenzied women on quests for obscure historical city facts or middle-aged men channeling superheroes. It's all a part of the madness that is the GO Urban Adventure Race. The race is part of a growing trend "civic exploration days" that have been ping-ponging across the country with the goal of getting people off the couch and out exploring their own cities. (Go Urban is a "technology based city-wide scavenger hunt loaded with physical and mental challenges.")

It works like this: each team of two receives four clues over text message, which lead to a specific location in the city. At each spot, teams are given a task, Amazing Race-style, and receive one additional clue via text. The first team to successfully solve eight clues and return to the finish line wins.  The San Francisco leg of the race is this Saturday, Sept. 19 beginning at noon at Great Meadows at Fort Mason and lasting until around 5pm (or when the last team finishes). Entries are $100 per team (cash only if purchased on race day), and can be booked online in advance through Active.com. The first place race winner will receive $400, the second place gets $275 and the third, $100. All teams who place receive free entry to the culminating event, the GO Urban Adventure Race Championships in Washington D.C. on July 17, 2010.