Work has started on a 310-metre-high Warsaw skyscraper by Foster + Partners, expected to become the tallest building in Poland.

The Varso Tower, or Warsaw Tower, is now under construction on a brownfield site next to the Warszawa Centralna railway station, with completion slated for 2020.

Featuring three staggered volumes, the building will be 310 metres at the its highest point, rising well above Poland's current tallest building: the 237-metre-high Palace of Culture and Science, also in the Polish capital.

Foster + Partners designed the tower as the flagship headquarters for real-estate developer HB Reavis. Containing 140,000 square metres of floor space, it will also provide flexible offices for international companies and smaller start-up businesses with views across the city.

A 230-metre-high observation deck – one of the highest in Europe – will be open for building users, locals and tourists, who will also have access to a restaurant split across levels 46 and 47.

On the ground floor, a glazed plaza on the ground will provide cafes and shops, while a series of covered streets inside the building will be open to the public all year round.

"We believe that Varso Tower will have a unique place on Warsaw's skyline, but most importantly it will establish a new destination capable of revitalising this urban quarter, right in the heart of the city," said architect Grant Brooke, who is leading the design team in London.

"The building contains high-quality and flexible office space, but it also makes an important contribution to the city with its glazed public courtyard at ground level and the spectacular viewing platforms with restaurants at the top."

"These public galleries offer panoramic views of the city to everyone," Brooke added.

The development will also include extensive new planting and street furniture, aiming to revitalise the surrounding area.

Hermanowicz Rewski Architects has designed a pair of buildings to accompany the Varso Tower, which will feature green roof terraces open daily for all occupants of the complex.

State-of-the-art technologies will be introduced to reduce electricity, water consumption and air pollution. The intention is that Varso will be the first project of this scale in Poland to receive a BREEAM energy efficiency rating of Outstanding.

Foster + Partners, headed by Norman Foster, ranked 13 in the Dezeen Hot List, a countdown of the most newsworthy players in the design industry.

The Varso Tower is one of a number of skyscrapers the firm has under development. Others include a set of twin buildings for Miami and the second-tallest building in San Francisco.