One of Tampa's best known road races regularly attracts elite runners and first-timers alike. The chief attraction is the 15K on Saturday, which takes runners along an out and back course from downtown Tampa, out just across Gandy Boulevard and back again alongside the mansions and water views of Bayshore Boulevard. The 5K and 15K is Saturday, and Sunday features an 8K and a half marathon. And then there's the Michelob Ultra Challenge, which consists of running the 15K, 5K, half marathon and 8K. Half marathon runners have to complete the race in under 2 hours 55 minutes to make it to the 8K start at 9 a.m. Whew! $25-$45, depending on race. Downtown Tampa, Intersecton of Twiggs and Tampa streets, Tampa. 6:45 a.m. Saturday, 6 a.m. Sunday.