From their event page: 

Fairmount Park Conservancy is thrilled to announce the much-anticipated return of Greenhouse Yoga at the Fairmount Park Horticulture Center on select dates throughout the winter.

Escape the winter blues and connect with your practice in the lush, tropical setting of the Horticulture Center’s greenhouse. These all-level classes take place on select Sundays and will be led by a rotation of experienced teachers from Tula Yoga.

ABOUT THE HORTICULTURE CENTER: The Horticulture Center in West Fairmount Park, a modern exhibition hall and greenhouse, was built for the Bicentennial Celebration in 1976. It sits on the site of the former Horticultural Hall, an 1876 Centennial Exposition building. Within its walls are a visitor center and greenhouse where one can see many tropical plants and a fine collection of statues interspersed in the greenery. To learn more about the Horticulture Center, you can visit their Instagram page.