The Market Gallery on the second floor of the St. Lawrence Market South occupies the former city hall council chamber, which operated here from 1845-99. After a 1978 renovation, the space became an exhibition facility for the city’s extensive art collections. The gallery’s signature fan windows, which once overlooked Toronto harbour, today overlook the main floor of the market.

This is a space where tech and innovation communities come together to develop game-changing health-care solutions. The Centre comprises four distinct laboratory buildings — the Princess Margaret Cancer Research Tower (operated by the University Health Network), Heritage Building (revitalized office/event space on the site of the former Toronto General Hospital), the South Tower (emerging companies) and the West Tower (established companies).

Located in the heart of downtown Toronto, this mosque — a former bank — serves as a city landmark and a symbol of Toronto’s multiculturalism and inclusion. Come and explore the site through guided tours and discover the building’s history, learn about the community’s heritage and diversity, have your name written in Arabic calligraphy and enjoy delicious cultural foods and drinks.

Massey College was built from 1961-63 following an architectural competition. At Doors Open, visitors will get the chance to see Ondaatje Hall and the Robertson Davies Library, sit in the Round Room and visit one of only three Royal Chapels in Canada. From 11 a.m. to 1 p.m., there will be a demonstration of a 19th-century letterpress shop.

The Mercer Union is a non-profit, artist-centred space in Toronto that presents innovative exhibitions by diverse Canadian and international artists in formative and established stages of their careers. Founded in 1979, it moved to its current space in 2008. Constructed in 1913, this building features decorative pilasters and ornate terracotta tiles on its façade. Original tin ceiling tiles also remain.

Since 1993, the Meridian Arts Centre has welcomed thousands of visitors, patrons, performers and artists through its doors. In 2015, Toronto City Council approved the consolidation of the governance and operations of Meridian Hall, St. Lawrence Centre for the Arts and Meridian Arts Centre into one new organization called TO Live. Come and explore the Centre during Doors Open.

Catch a lawn recital of the Met's 54-bell carillon before entering this church. Take in the rich woodwork, enjoy a guided tour, explore a visual history display and watch pipe organ demonstrations. You can even take a bell tower tour to get up close. For Doors Open, experience a special presentation of Norval Morrisseau's "Family of the Spiritual Journey."

This building is considered one of the finest examples of Loyalist or late-Georgian architecture in Ontario. Original owners Thomas and Margaret Montgomery, Irish immigrants, operated it as a tavern until Margaret's death in 1855. The inn has been restored as a mid-19th-century tavern, a reminder of the pivotal role that inns played as community hubs in the settlement of Ontario.

For over 20 years, the Museum of Contemporary Art Toronto has featured the work of 1,100-plus Canadian and international artists. In 2018, they moved into this purpose-designed space in the Junction – once Toronto’s tallest building. The original factory produced aluminum products for the Second World War. When it opened, it was considered innovative because it used concrete slab architecture.

The Muslims in Canada Archives is housed within the Jackman Humanities Building at the University of Toronto. Designed in 1929, the building was constructed to provide facilities for the medical profession. The preserved stone detailing and grand lobby are key features of this designated building. The fifth-floor offices exhibit archival materials relating to the historical presence of Canadian Muslims.

In 2020, the Nia Centre for the Arts embarked on its most ambitious project yet. It renovated its 1,300-square-metre (14,000-square-foot) space into Canada's first professional multidisciplinary arts facility dedicated to Black artistic traditions. Located in the heart of a historically Black neighbourhood, the new facility features a performance space, youth-designated space, a digital media lab, event space and more.

The Nursing Simulation Centre allows York University's nursing students to achieve their professional development/learning goals. Located on the third floor of the Health, Nursing and Environmental Studies building, it can be divided into two unique spaces — the Nursing Skills Lab and the Computer Skills Lab. The Nursing Skills Lab houses adult medical-surgical beds, a pediatric area and isolation two rooms.

OCAD University is Canada's oldest and largest art and design university, located in downtown Toronto since 1876. The main campus includes the George Reid House and the iconic Rosalie Sharp Centre for Design. Home to over 4,500 students, its classes are taught by experts in their fields. Come and explore this beautiful facility and learn more about what they offer.

The imposing Old City Hall was Toronto’s third city hall. The lobby features one of the city's few secular stained-glass windows. Original gargoyles were replaced in 2002 with replicas. And, in 1925, a cenotaph was erected outside to honour Torontonians who died in the First World War (later updated for veterans of the Second World War and the Korean War).

The Old Don Jail served as a prison for 113 years, closing in 1977. After years of stagnation, the property was purchased by Hennick Bridgepoint Hospital as part of its new campus. The modern hospital, with its 150-year history in Toronto's Riverdale community, is connected by a glass bridge to the historical jail, which now serves as its administrative building. (Photo: Richard Adams)

The headquarters of the Ontario Association of Architects is more than the regulator of the province's architecture profession. It is the public and physical embodiment of architects, skills and aspirations. On your Doors Open tour, explore recent renovations that have helped the building become net-zero — including an energy-efficient geothermal system, solar panels, improved daylighting and tint-changing dynamic windows.

Osgoode Hall — home of the Law Society of Ontario and the highest courts of the province — opened in 1832 and remains a Toronto landmark and symbol of the law in Ontario. The 1867 fence, renowned for its peculiar gates, surrounds the property and its landscaped grounds. Download the self-guided tour or speak with the knowledgeable volunteers. (No tripods allowed.)

The Parkdale Arts and Cultural Centre was the City's Police Station — 6 Division from 1931-63. The building now has nine active work studios for artists, as well as community offices and an art gallery, Gallery 1313 (once the site of 12 holding cells for prisoners). The art deco clock above the main entrance was repaired but is not currently functioning.

People Design Co-op's architecture studio is located on the second floor of a former bank building. They work with non-profit and public housing providers, social service providers and community land trusts to retrofit and develop affordable housing stock. The City has identified this property through the 2014 Leslieville Planning Study as significant for its prominent location and its unique typology.

The Polish Combatants' Association Branch 20, a non-profit organization founded in 1948, is dedicated to honouring the memory of Polish veterans and promoting Polish history, culture and language. The three-storey building includes an underground parking lot, offices, a dining room, banquet hall and military museum. The building has a rich history and holds great meaning for the Polish-Canadian community.

The Potter's Studio, established in 1972, has been a major contributor to the ceramic community in Toronto with workshops and classes. It recently relocated to this Scarborough location. Come and visit the large, bright, airy studio and experience the potting process — from wheel throwing and hand-building to glazing and firing pots. Warning: Some visitors may find this craft addictive.

Project Studio Architects developed a laneway/garden suite initiative using shipping containers to cut both construction costs and time drastically. One of the earliest completed suites was here at 339 Boon Avenue. Based on the success of the prototype as a functional space, and to adhere to the work philosophy of "practise what you preach," the firm relocated its office there.

Celebrating 20 years, Q4 Architects is the largest woman-owned and -led architectural firm in Canada. They are focused on designing residential and mixed-use projects with a sense of dignity, at all levels of affordability. This studio is perched above the West Don River, with sweeping views of the ravine. Come and explore the studio's boardrooms, creative studio and collaboration spaces.

Constructed in the 1930s, this popular Doors Open site is Toronto’s largest water treatment plant, providing 400 million litres of safe drinking water daily. It’s also the largest ensemble of art deco structures in the city. Take a self-guided tour and explore the pump house and filter building, with staff available to answer questions along the way. (No tripods/filming allowed.) (Photo: Samuel Kolber)

RAW Design's new office showcases the firm's dedication to adaptive reuse and sustainable design. Originally a one-storey mechanic’s garage, the building has been transformed into a two-storey structure featuring timber construction. The newly added second floor houses RAW's office, while the ground floor remains a vibrant commercial space. This project highlights RAW's innovative approach to creating functional and community-focused architecture.