This state-of-the-art facility is the newest addition to the Lemont Park District. The CORE features a fitness area with more than 100 pieces of equipment, towel service and free weights. Personal training and massage therapy are available to members, as well as an array of aerobics, pilates, yoga, kickboxing and dance classes. The CORE also has a six-lane swimming pool and a 21,000 square-foot gymnasium with basketball and volleyball courts. Childcare is also available throughout the day.

The Lesnieski Center is connected to Lemont's "CORE" Fitness Center and does feature weight rooms.  However, the center is specifically used for large-gathering rentals such as reunions, birthday parties, and even wedding receptions.