Markham Web Content Viewer (JSR 286)




Heintzman House is one of the oldest building in Thornhill — Markham. It features the earliest mudhouse in the province. Made of adobe brick, fired brick and fram construction, it is also known as the Sunnyside Manor Farm.

In 1798 this property was awarded to United Empire Loyalist, Anthony Hollingshead.

In 1817, possibly upon the death of Anthony, the Hollingshead family sold the property. Based on land registry records, the second owner was the Honourable George Crookshank of York (Toronto). George, the son of a Loyalist, was a prominent member of Upper Canada society devoting much of his professional career to government service. He transformed the farmhouse into a 13-room mansion.

Over the years, the property passed through many hands before the final private owner, Charles Theodore Heintzman, purchased it in 1930. The Heintzman family is famous for their piano business.

In 1984 the Heintzman House received designation as a heritage site under the Ontario Heritage Act.

Contact Information

For inquiries please contact 905-944-3800 extension 6609 or

135 Bay Thorn Drive  
Thornhill, ON   L3T 3V1