The court has a tessellated glass roof, engineered by Buro Happold and built by Waagner-Biro, covering the entire court, and surrounds the original circular British Museum Reading Room in the centre, now a museum. It is the largest covered square in Europe. The glass and steel roof is made up of 4,878 unique steel members connected at 1,566 unique nodes and 1,656 pairs of glass windowpanes making up 6,100m2 of glazing; each of a unique shape because of the undulating nature of the roof.