June 10, 2012 (La Mesa) -- The La Mesa Centennial-themed Amazing Geocache Challenge is officially on, and anyone who appreciates a fun and family-friendly modern-day scavenger hunt is encouraged to participate – and possibly win prizes along the way. Officially started on June 2 to coincide with the city’s Flag Day Parade, the Challenge concludes at 5pm October 7, 2012, with the City’s other beloved event, the La Mesa Octoberfest.