Walkway and stairs to the 3rd floor.
An architectural design competition to design a building for the contemporary arts museum was held in 1992. The winning proposal, titled Chiasma by Steven Holl from the US, was selected from the 516 submitted entries.
Construction work began in 1996, and the museum opened in 1998.
en.wikipedia.org/wiki/Kiasma
In neuroanatomy, the optic chiasma is the part of the brain where the optic nerves cross.