Playing with the human eye, brand new stadium in Zaozhuang is almost see-through, while its roof hangs gently above. It was a tremendous task to deliver such structure and one that was completed with grace!

Not that long ago, in 2009, this place was a small village. But already then relocation was imminent. Competition for design of Zaozhuang's largest sports and cultural centre was already ongoing, to be decided between 9 international teams. That former village was precisely where the new main axis of the city runs.

It now goes straight through the stadium, too. In fact, it was specifically designed as almost entirely see-through, connecting the mountains in the south with fresh representative district in the north. Lack of second tier of seating in the north also allows spectators inside the stadium to take a peek of the park below.

© Yaoli / 姚力, United Atelier

With almost 50 hectares of total space, the project presented several major challenges to the architects. First, land slopes singificantly towards the north. Reintroducing natural waterflow back to the site was demanded to form small streams interwoven with pedestrian paths. On top of that, the goal was to reach high standards in ecology and sustainability.

The winning design by United Atelier, under Alain Robert's leadership, used the challenges as advantages. As much of available land as possible was left as it was, naturally sloped. Thus the layout of pathways and landscaping similar to map contours. Reintroduction of water flow was done along with system of water recollection from rain, later used throughout the complex. Combined with energy efficiency and low consumption of materials (roof 80% lighter than classic steel girders) this allowed application for LEED certification.

© Yaoli / 姚力, United Atelier

Pedestrians walk around the nearly-50-hectare area through a system of pathways and ramps. The height difference means that visitors arriving from the south walk down towards the stadium, while those coming from the north climb to the top of cascading stairs. Connection between all crucial elements of the complex – like tennis courts in the south, training stadium in the west, commercial and cultural areas in the north – proves very efficient, almost walking visitors through the area.

The main stadium began winning awards soon after its completion and no wonder, it has one of the most complex tensile cable roofs ever created. The upper ring is twisted, connected by inter-crossing cables, resembling a classic bicycle spoke wheel. When designed, it was the first of its kind globally as such layout – while resulting in impressive roof pattern – is an engineering challenge on many levels.

© Yaoli / 姚力, United Atelier

All of the roof is connected by PTFE membrane. There are 48 segments on top and 24 others, flowing onto the outer structure (43,000 m2 in total). As a result, the roof seems like a crowd hovering above the stadium, high over the auditorium. That impression wouldn't have been possible if not for the lack of traditional facades. The building isn't just openwork, it's almost entirely open thanks to a visibly light hollowed-out steel skeleton. While it doesn't serve as roof support, actual columns were smartly hidden inside the stadium.

The 30,000-seat auditorium may not be the biggest but surely easily accessible, as the lower tier is entered directly from the public concourse. The building offers 57,000 m2 of floor area. In total it consumed some $100 million, while all of the complex was estimated by local authorities to cost 460 million.