Our Lady of the Assumption Church is the oldest continuous parish in Upper Canada (Ontario) and was first founded in 1728, on the shores of the Detroit River. One of the most beautiful and magnificent heritage buildings in Ontario, it was established by the Jesuits and French settlers on land donated by the Huron First Nation.

In 1747, the first Jesuit Mission in all of Upper Canada was established in what would become Sandwich Town. The Parish would remain an important centre of community activity in Sandwich; indeed, it was the Parish that established Sandwich Town’s very first schools and school board.

The Church building is an important cultural resource to Windsor and to Canada: the site is one of the most important locations from the earliest history of European exploration and settlement in what is now Southwestern Ontario, where French and Native peoples shared a community. The current Church building is over 160 years old, having been constructed in 1842-1846.

In addition to possessing provincial heritage recognition, Assumption Church is also recognized by the City of Windsor under the Ontario Heritage Act, having been designated as architecturally and historically significant by the City in 1975; it can also be found on the Canadian Register of Historic Places. The Church is one of Ontario’s most important religious landmarks from the first of half of the 19th century, and the Assumption parish has been closely associated with the Francophone community in Southwestern Ontario.

Fifteen years after the Church’s construction, Assumption College was built on a property adjacent to the church and was the foundation for today’s University of Windsor; it remains an integral part of the campus.

The Church has long been recognized as one of the Diocese of London’s most precious assets and would be impossible to replace the church building in terms of its heritage value. Assumption Church can well be considered a local and national treasure.