What: 50k, 35k, half marathon and 13k races at Overlook Park in Auburn. The website singletrackrunning.com describes the 50k, a UTMB World Series qualifier, as “one of the most challenging in the Auburn/Cool area” with more than 6,000 feet of climbing on four hills: Cardiac, K2 (aka Training Hill), Knickerbocker (the old Auburn Dam site) and Overlook. There were 187 finishers in the most recent February race.