Far from the corporate-chain experience, the 20th Street Gym is the workout facility of hard knocks. The city's oldest rec center, located in the heart of downtown, 20th Street is a no-frills training facility, complete with a fully stocked weight room, shiny cardio machines, an indoor pool and basketball court, and weekly yoga and spin classes. But the best workout in the city comes from the gym's boxing program, offering real in-the-ring training for kids and adults alike. The grownups' classes are a nonstop circuit involving a speed bag and heavy-bag hitting, jumping rope and one-on-one guidance from expert coaches — something that no chain health club can match.