Construction of Toronto's tallest residential tower is now officially underway at the corner of Yonge and Gerrard.

Mayor David Miller and local Councillor Kyle Rae attended the groundbreaking ceremony Friday morning along with the team behind Aura – the name of the 75-storey building.

The condominium is slated to have 931 residential suites including an 11,000 square-foot penthouse selling for $17.5 million. The building's units are 97 per cent sold.

"We went through a period last year when the market was slow, but now that interest rates are at record lows, you're seeing a ton of people moving back into the real estate market," said Riz Dhanji, vice-president of sales for developer Canderel Stoneridge.

The residence will be built on top of the city's busiest transit hub and will include 150,000 square feet of retail space. Bed Bath and Beyond, Alice Fazooli's and Canyon Creek are said to be among the restaurants and stores that will occupy the bottom of the building at the northwest corner of Yonge and Gerrard.

"If we want Toronto to succeed, we need to build inside the city," said Miller. "This building will be built to green standards and will revitalize Yonge Street."

Units at the building are 97 per cent sold out, according to officials. Miller said this is a sure indicator that Toronto's condo market continues to grow, despite the recent recession.

Miller said it's been 30 years since he's seen a condo boom this strong. There are currently 35,000 condo units under construction in the city.

"It's also a sign of confidence in Toronto and that our policy for low development charges for example are working," Miller said.

Analysts have said demand could remain high well into the future. With a constant stream of newcomers to the GTA, the only way to provide housing is to go up, they say.

"Buildings like this will help do that," said James Robinson of the Yonge Street Business Improvement Area. "Downtown needs to be intensified."

With a report from CTV Toronto's Naomi Parness