The 20th Street Gym isn't fancy — which is all the more reason to take advantage of this rec center in the city. All of the average gym amenities are here — indoor pool, weight room, cardio equipment — and are paired with a schedule packed with pickleball games, pottery classes and Pilates. Almost as historic as the building itself is the gym's boxing program, offering kids and adults of all skill levels a chance to be trained by professionals and compete in the ring. The soaring windows and wooden rails of the grand staircase are reminders of the gym's antiquity, but it's the no-BS workouts and knowledgeable staff of teachers and trainers that bring the 20th Street Gym into the 21st century.