If you like to explore places that are generally inaccessible to the public or to get a better sense of the various small towns that surround Toronto, there's an excellent way to accomplish both tasks this summer. Doors Open Ontario offers access to many unseen spaces across the province, which should make for some thrilling road trips.

Here are some of the most intriguing places to check out this spring and summer.

Whitchurch-Stouffville - June 3

The highlight of Doors Open in this small town northeast of Toronto is the Jean-Baptiste Lainé Archaeological Site, which is one of the largest Huron-Wendat sites ever found and dates back some 500 years.

Northumberland County - June 3 and 4

Here's a rare chance to get an up close look at one of Ontario's best examples of Neoclassical architecture. The Barnum House was built in 1819 and played host to a number of generations of the family before it eventually was designated as a National Historic Site.

Ottawa - June 3 and 4

If you're willing to make the longer trip to Ottawa, there's a host of promising sites to explore. For my money, the Diefenbunker is at the top of the list, but the Supreme Court, Royal Canadian Mint, and the Lemieux Island Water Purification Plant are also highlights.

Bradford West Gwillimbury – June 17

This year there's an intriguing opportunity to get a behind the scenes look at the technologically advanced Bradford West Gwillimbury Wastewater Treatment Plant. It's remarkable to learn how water is treated before it's returned to the natural environment.

Elora and Fergus - June 17

Both of these towns are worth visiting in general for their idyllic commercial strips and nearby attractions like the Elora Gorge, but during Doors Open you can get an up close look at the Elora Mill, which has been closed for renovations for ages.

Gravenhurst – June 24

Muskoka has its fair share of stunning buildings, but the Gravenhurst Opera House is one of the finest. The Ontario Heritage Trust's Sean Fraser describes it as "a medieval looking space with a grand hall and wood hammer beams." There's also Norman Bethune House to check out.

St. Catharines – June 24

The gem of Doors Open Ontario this year has to be the behind the scenes tour of the Decew Falls Generating Station. This is a massive structure that's been in continual use since 1898. Witness the spectacle of how power being harnessed.

Thanks to Sean Fraser of the Ontario Heritage Trust for his recommendations.