On September 16, 1908, William Crapo Durant filed incorporation papers that formed a new company he called General Motors.
He was already involved with Buick, and he'd agreed to license their production to the McLaughlin Motor Car Company in Oshawa, Ontario. Its founder, Sam McLaughlin, sold his company completely to GM in 1918 (it became GM of Canada) but stayed on as president and as a board member of the U.S. company. He also built a little place in Oshawa that he called Parkwood.
The 55-room mansion is now a public museum and national historical site, and if you spend any time watching movies, you've probably seen it; it's been the backdrop for such films as X-Men, Hollywoodland, Chicago and Billy Madison.
In honor of GM's 100th anniversary, it'll be holding a number of events throughout the year. The one I'm most looking forward to is the McLaughlin Buick Club's Homecoming on August 4, when it's expected that 200 vintage vehicles will drive up Oshawa's main street and into the grounds.
All the info on Parkwood can be found here.