Renovation of the interior of the Amphitheater in the cylindrical building of the old gasholder of the industrial gas park of Athens. Perceived as a new tank defined through the new folding and flowing topologies, the amphitheater was designed as an "acoustic device". The design of the roof enhances passive acoustics by designing geometric sound-reflectors and sound absorbers, oak surfaces, that form prismatic pyramid clusters of different typologies. It consists of 564 pieces belonging to basic typologies, sub-typologies and uniquely designed pieces, all custom designed and fabricated.