 The structure for the blocks was a challenge . At first , the design team had considered switching to plastic blocks , until the team found Circle <unk> Inc . , a prefabricated glass panel company in Melbourne , Florida which specializes in structural glass panel systems . Circle <unk> came up with the plan of turning <unk> on their sides to be used as building elements . The individual <unk> are 5 feet ( 1 @.@ 5 m ) tall and either 16 feet ( 4 @.@ 9 m ) or 23 feet ( 7 @.@ 0 m ) wide with cell capacity of an average of 250 blocks . Each tower is composed of 44 <unk> stacked and <unk> . The combination of the refraction of the glass and the <unk> of the metal make the grid virtually invisible . 
