Fuelled by a decade-long boom in the tech sector, Seattle's real estate industry has been in great shape for the past few years. The city's streets are being transformed by new developments, and nothing seems to stop the insatiable need for more office and residential spaces. As a consequence of the high pressure experienced by the market around Elliott Bay, newly proposed developments are now reaching unprecedented heights. While there are a number of towers currently under construction in the city, today we take a look at the five highest proposed and/or approved projects in downtown Seattle which, if completed, will once again transform the skyline of the Pacific Northwest's largest metropolis.

The Seattle Skyline, image by Nicolas Arnaud-Goddet

At the corner of Fourth Avenue and Cherry Street, across the street from the Columbia Center — Seattle's current tallest building — Miami-based developer Crescent Heights intends to build the city's next tallest tower, consisting of a mixed-used 339-metre, 101-storey edifice. Designed by LMN Architects, 701 Fourth Avenue would become the tallest building on the United States' West Coast if approved. The design includes 1,200 residential units, 150 hotel rooms and close to 15,500 square metres of office space. No completion date is currently available for this project.

701 Fourth Avenue, Seattle, United States by Crescent Heights and LMN Architects

Immediately to the west, on the entire city block delineated by Second and Third Avenues, and Marion and Columbia Streets, Urban Visions is proposing a 271-metre or 888-foot tower. Named 888 2nd Avenue in reference to its height in feet, the tower will boast mixed used spaces across 60 storeys, 16 of which will consist of residential units. Designed by local firm NBBJ, the building will feature a 187-metre-high atrium at its centre in order to bring natural light into the heart of each floor plate. Tentatively scheduled for completion in 2019, it will become Seattle's second tallest building until its peer at 701 Fourth Avenue pushes it down to third tallest.

888 2nd Avenue in Seattle, image via Urban Visions and NBBJ

Further north, along the stretch of Union Street located between Fourth and Fifth Avenues, developer Wright Runstad & Company has commissioned NBBJ to design an edifice to replace the mall that is currently occupying the lot next to Minoru Yamasaki’s famous Rainier Tower. Once again, this 259-metre development will offer a mix of uses. Indeed, the ground floor will be home to the retail component, while levels two to 37 will offer ample office spaces. Above, 216 residential units will occupy the top floors with the highest penthouse located on the 58th level. Finally, at the corner of Fourth Avenue and University Street, a 12-storey, 155-room hotel will be built. Recently approved, the Rainier Square Tower will be fully complete by 2019, although the first office workers will be able to move in some time in 2018.

Rainier Square Tower in Seattle, image via Wright Runstad & Company and NBBJ

At 1015 Second Avenue , the currently empty Federal Reserve Bank building might receive a 47 storey addition. Constructed above the 1950s structure, the Perkins + Will -designed tower will add approximately 50,000 square metres of new office space to the downtown area across 32 floors topped by 12 levels divided into 192 residential dwellings. Martin Selig Real Estate is currently seeking approval for the 202-metre tower, which might take longer than usual since the older existing building is listed on the National Register of Historic Places.

1015 Second Avenue in Seattle, image via Perkins + Will and Martin Selig Real Estate