The structural steel supports for the new Downtown Arena in Sacramento have begun going up, as construction continues on what is expected to be the first California arena to gain LEED Gold certification.

LEED – Leadership in Energy and Environmental Design – is a certification scheme to recognise new structures built with eco-friendly principles in mind.

In the case of the Downtown Arena, one of the greatest achievements has been the high percentage of recycled materials used.

Of the previous structures that were demolished on the site, more than 98% has been recycled, beating both the legal minimum of 50% and the project’s own original target of 75%.

Some 100,000 tons of materials have been recycled, including over 6,500 tons of metal.

However, one recycled structure that won’t become a reality is the 52-foot “world’s smartest cowbell”, announced on April 1st by the arena’s future occupants, NBA team the Sacramento Kings.

“Made of 100% locally sourced, recycled cowbells, the structure will have the names of prominent local cows throughout Sacramento history inscribed in the outer frame,” the team joked in their April Fool’s Day ‘announcement’.

However, the structural steel going up this week will be accompanied by a steel sculpture, although not in the shape of a cowbell.

Jeff Koons’ ‘Coloring Book’, a steel sculpture designed to capture the enthusiasm of childhood, will go on permanent display in the plaza outside the arena, which is due to open in autumn 2016.