Richard Serra at The Guggenheim, Bilbao

The problem with the Guggenheim Museum in Bilbao is that Frank Gerry's building will always upstage any art that is in it. The building is the star of the show.

Having said that it is hard not to be impressed by Richard Serras' monumental ensemble of steel sculptures The Matter of Time, which occupies the entire space of room 104 on the ground floor, the largest gallery space in the museum.

Now a permanent exhibit, it is hard to imagine the museum without these massive steel forms. Perhaps not as selfie friendly as Jeff Koons' iconic flower sculpture Puppy, or Louise Bourgeois' giant bronze spider Maman (which are also permanent fixtures), they do have a weighty presence.

To my mind they are slightly diminished, domesticated, by being contained within a room, however large. They should be outside in the elements, and where light and shadows can play on their curvy forms.