Heintzman House (circa 1817) also known as Sunnyside Manor Farm is one of the oldest homes in the GTA with a fascinating history and has been home to many of Thornhill and Markham's leading citizens. In 1984 the Heintzman House received designation as a heritage site. This renovated historical house now operates as a rental facility for private and community functions. We can accommodate up to 120 comfortably seated and 140 for cocktail style functions. A beautiful place to hold your wedding ceremony, photos and reception. Bridal party change rooms, gorgeous grounds and on site parking. more... See more text