Like the framework of a mighty skyscraper, the core helps humans hold up the weight of the sky. Stay firm against the firmament with today's Groupon: for $15, you get two group classes at Cor Pilates LLC (a $30 value).

In a renovated historic studio with exposed brick walls, high ceilings, and bright windows, the expert instructors at Cor Pilates help students mold their muscles, build power, and fortify their cores for better balance and posture. The Pilates Stretch for Beginners class features long, gentle extensions that can be tailored for those with joint pain or uncalibrated wristwatches. Students in the Matwork class modify movements with bands, rollers, and adverbs to increase or decrease the challenge according to ability levels, and guests in Cor Bar: Fitness are served a cocktail of ballet barre exercises, Pilates, and dance movements designed to burn fat, tone muscles and prepare pupils for vigilante performances of Swan Lake.