RAU Architects and Ro&Ad Architects have designed the egg-shaped Tij Observatory for the Scheelhoek Nature Reserve in Stellendam, the Netherlands.
Designed for birdwatchers observing the Sandwich terns that nest off the coast of the island of Scheelhoek, the observatory takes its form from a tern's egg.

Amsterdam studio RAU Architects, in collaboration with Ro&Ad Architects, clad the rounded form in thatched reeds from the local nature reserve.
Tij Observatory, which translates as Tide, is one of a series of commissions funded by the Dutch lottery. It was built to celebrate the opening of sluices at Haringvliet, an inlet of the North Sea that was originally closed as part of the Delta Works in the 1960s.

The bird-egg's frame was parametrically designed to determine the best shape and position of openings. It was built using a file-to-factory system, with 402 parts delivered and assembled on-site. Designed to rest lightly on the nature reserve, it will be easy to dismantle and move if required.

"By building everything in such a way that everything can be taken apart without losing any of its value, we ensure that the strain on the ecosystem is minimal," said Thomas Rau, founder of RAU Architects.
"Thanks to its complete rebuilding capabilities, modularity and materialisation, it fully meets all the key point for a sustainable structure with circular potential."

Materially, this timber frame is divided into two. The bottom section, which is...