Here are two spots that CBC's Our Toronto explored in advance of the weekend of urban exploration:
Charles Pachter's home studio
Like the the messy garage artist Charles Pachter works. The well-known artist is opening the door to his workplace, gallery and home — all behind the same door.
"It's the ideal situation," says Pachter. "Where I live up on the top floor is far enough away from all of this that I can close all the lights down here in this building and then go into the other space."
Pachter turned a dilapidated old building and parking lot into his dream space with the help of an architect, Steve Teeple.
"I said to him, 'What do you think are my chances of building my dream home in the empty parking lot?' He said, 'You know I think you'd have a hard time anywhere but here. We're in Chinatown. Let's give it a try,'" Pachter recalls.
"He came up with this brilliant concept of these stacked cubes made out of steel and glass in the front."
This year's Doors Open theme is secrets and spirits — perfect for what originally stood in this space.
"Looking on title we found out it was an old Jewish immigrant funeral home built in 1912, and because the theme this year for Doors Open is about ghosts, it seemed liked the ideal thing to do to think about the ghosts of the past coming to haunt us," says Pachter.
Pachter has only felt good spirits in his home, completed in 2005, he says.
Gibraltar Point Lighthouse
When the Gibraltar Point Lighthouse opened in 1808, it became the first stone building in Toronto. It's now the oldest lighthouse in the Great Lakes region.
For Doors Open weekend, you can explore the lighthouse from top to bottom — 90 stairs in total.
When it first opened, the lighthouse was run on whale oil, before it converted to coal gas. Around the 1910s, it became an electricity powered lighthouse.
But it has always been shrouded in mystery.
The CBC ran a report in 1958 about Gibraltar being haunted, reporting that hundreds of people saw ghostly paranormal happenings in and around the lighthouse.
As the story goes, the first lighthouse keeper, J.P. Radan Muller, was killed by soldiers from the nearby Garrison in a dispute over beer.
For whatever reason, they chased him up to the top of the lighthouse and had him cornered and clubbed him over the head.
For the last 200 years, he's come back to wander around the area. People claim to see him going through the door and see the light go on and off.
In the 200 years since it was built, it has lived through incorporation, rebellion, invasion by Americans, Toronto becoming a city in the 1830s, and the construction of the CN tower and the condo towers that we have today.
See the Doors Open website for more details.