For me, the highlight of this weekend’s Doors Open Toronto festival was the official opening of the green roof at City Hall.

South view from the green roof

It’s only the first stage in a larger renovation of City Hall and Nathan Philips Square (see here for my take and background information). But already, the designers have created one of the city’s most remarkable public spaces: 35,000 square feet of garden, planted within the concrete, sandstone and glass of downtown.

To be precise, the designers - including PLANT Architect, Shore Tilbe Irwin, and Adrian Blackwell – didn’t create the space; they’ve reactivated this area on top of City Hall’s podium, which was an integral part of the 1958 design by Viljo Revell but has been empty and dormant for 20 years. (For history, see my last post on this or the city’s page here).

It’s a revelation. The space itself is already gorgeous, with arresting, colourful plantings by PLANT and beautiful furniture designed by Blackwell out of ipe and black steel. It has the magic-green-carpet quality of many green roofs, on a massive scale. Once the plantings fill in, it’ll make an excellent aesthetic argument, as well as an environmental one, for more green roofs. This is exactly what the city is hoping for.

But the design also illuminates the architecture of City Hall and Nathan Philips Square. The council chamber (see first pic below) is wrapped inside a mushroom-shaped volume of concrete. There is a complex series of connections between this central volume and the surrounding towers, but they’ve been closed or hard to navigate.

City Hall interior, Flickr photo by Darajan

Now, with the podium open, there are clear connections between the towers, and people can spill out from within City Hall. That includes the marriage office nearby. When I was there for the official opening Saturday, Mayor David Miller told a story about the night before: a just-married couple had wandered out onto the roof, which was open for an event with 1,000 mayors in town for a conference. They got a surprise ovation. Funny, but the same thing happened just after Miller spoke: a happy couple in white dress and black tie came out into the crowd and stood there, a bit dazed, as visitors with long-lens cameras and high-school kids on stilts streamed past them. It felt like something great was getting started, and not just for those two newlyweds.

Opening ceremony; Flickr photo by PJMixer

View of the council chamber from the southwest

Eastern edge of the roof, looking north

Behind the towers, looking west

..and a full aerial view

EDIT June 4: New image at top of post.