The Matter of Time (in Spanish: La materia del tiempo) is an installation comprising eight pieces of torqued ellipses made of weathering steel (COR-TEN steel), by the US sculptor Richard Serra.
It incorporates a series of seven sculptures[1] made of spot-welded sheets of steel that form 14-foot (4.3 m)-high curling walls[2] positioned around the existing sculpture, Snake (Serpiente), that had been commissioned for the museum's opening in 1997.
Commissioned by the Museo Guggenheim Bilbao, it forms part of the permanent exhibition since 2005.
[2] Made at the rolling mill at Siegen, Germany,[2] and weighing in total 1034 tonnes,[4] it is installed in the museum's main gallery, the 430-foot (130 m) 80-foot (24 m)[4] Arcelor Gallery, named after its sponsor,[1] but originally known as the Fish Gallery.
[5] Arranged "to move the viewer through them and through the space surrounding them",[6] the installation comprises the following pieces (in order of proximity to the entrance):