Shell Centre, Modern office skyscraper in downtown Calgary, Canada

Shell Centre is an office tower in downtown Calgary, Alberta, rising to 140 m (about 460 ft) across 33 floors. The building has a figure-eight footprint, which means every floor wraps around two rounded cores and produces a high number of corner offices.

Olympia and York Developments announced the tower in February 1975 as a $35-million, 33-storey project on the site of the former Caravan Hotel, its first development in Western Canada. Shell Oil became the primary tenant during construction, consolidating 1,000 Calgary employees and giving the building its name. It opened in 1977 as Calgary's fourth-tallest building and was renamed 400 4th Avenue in 2024 after Shell Canada moved to the Bow.

The Calgary Herald described the tower as a turning point for corporate offices in the city, replacing the plain towers common before with marble and granite skins then usual in American cities. The cladding is 1.25-inch-thick slabs of Italian granite, and the figure-eight plan yields eight corner offices per floor.

The recessed lobby is reached from street level behind a row of supporting pillars, so look for the gap between them rather than a conventional front door. The tower is a working office building; public access is generally limited to the lobby. One underground parking level holds 86 cars.

The figure-eight footprint was a rare choice for office towers in North America when the building was completed, and it required engineers to solve load distribution problems that a standard rectangular plan would not have posed. The exterior is clad in Italian granite, which was an uncommon material for a Calgary office building at the time.