Architecture practice Close to the Bone have blurred the boundary between a stairway and an observation tower by building a gravity-defying monument in a Belgian forest.

The studio were commissioned to build an observation point in the municipality of Tielt-Winge, after a popular wooden lookout tower was destroyed by arsonists.

The brief called for a new landmark that could survive the elements and attack from vandals. Their solution was Vlooyberg Tower; a huge metal stairway that raises up from the ground seemingly without support.

“Instead of a conventional construction with a spiral staircase, we conceived a suspendedvolume without too many decorative frills,” said the studio in a statement. “Modelling the Vlooyberg Tower was a war against its own weight.”

The tower is more than 11m (36ft) tall and and is built on a galvanised sub-structure clad in weathering steel; a subtle reference to the red-brown colour of the ironstone found in the region

To ensure that the structure would be strong enough and would not sag, Close to the Bone manually calculated the forces acting in each element and selected a suitable form and dimensions. As a result, the tower weighs less than 13 tonnes.

A railing wall functions as a structural beam that makes the steel structure strong and stable enough to withstand the forces acting on it, while two shock absorbers stop the tower from vibrating under foot.

The structure was fully prefabricated and assembled on site section by section in just half a day.

“The tower enters into a dialogue with the surroundings and is placed in juxtaposition with respect to the environment,” said Close to the Bone.

“As a landmark with strong iconic value, it both literally and figuratively raises the profile of the beautiful region – an intriguing monument for locals, passers-by and fans of modern architecture.”