Mexican artist Santiago Borja has built a thatched observatory on the roof of one of Holland's best-preserved Modernist houses (+ slideshow).

Named A Mental Image ? Blavatsky Observatory, Borja's installation has been constructed on top of Sonneveld House in Rotterdam, a property designed in the 1930s by Dutch firm Brinkman & Van der Vlugt.

The heptagonal structure transforms the simple roof terrace into an outdoor room that focuses visitors' attention to the sky above.

Timelapse video showing the observatory from day to night

Its angled surface is thatched with straw, intended to reference the traditional Dutch farmhouse, but also to directly contrast the white walls and functional styling of the historic house.
"Borja considers his observatory to be a space for contemplation, an abstract space where visitors can find themselves through spiritual and spatial awareness," said a statement from the project team, led by curator Erich Weiss.

"[He] covered his observatory with a thatched roof in acknowledgement of traditional Dutch construction methods," they added.

Albertus Sonneveld, one of the three directors of the Van Nelle Factory, commissioned Sonneveld House for himself and his family in 1929. Since 2001 it has operated as a museum, run by the Het Nieuwe Instituut of architecture, design and e-culture.

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