I'm trying to remember what made me think of this. I'm coming up blank.
In 1995, Geert van de Camp, Andre Dekker and Ruud Reutelingsperger decided to work together to create space which facilitated longer-term contemplation. They called their collaborative Observatorium.
In 1997, they set up their second Observatorium structure-- in this case, a small, modernist house-like space made mostly of plywood bookshelves--at Snug Harbor Cultural Center on Staten Island. You could arrange to stay in it for 24 hours, a day and a night. It was like Rirkrit's apartment replica at Passerby, but only for one person at a time. Like De Maria's Lightning Field, only turned inward, for communing with an interior landscape.
Somewhere over the years, I'd gotten it in my head that the Observatorium was by another Rotterdam-based collective, Atelier van Lieshout, and I'd periodically try unsuccessfully to find it again.
Here is the Observatorium website [observatorium.org]
And their blog. [observatoriumrotterdam.blogspot.com]
Look, they're at the Marin Headlands now, organizing a residency/workshop to address the use of the old Fort Barry Gymnasium building. [opentotheelements.wordpress.com]
They have a new book: Observatorium: Big Pieces Of Time [6 to 9 weeks?]