*2023 stock. 50 copies limited editon in special wooden pack art cover'.* A handmade art object of the work has been published in a limited edition of 50 copies by label Aloardi. It is a wooden pack made with the laser cutting technique, in a design based on the maps of the Maastunnel. It contains an USB pendrive with the documentary, including a bonus audio track, and an audio tape with the soundtrack.

Invisible Architecture is a project by Christian Galarreta and Janneke van der Putten. In this edition they research the acoustic qualities of a monumental site, a 500-meter-long tunnel under the Maas River. The Maastunnel (Rotterdam, The Netherlands) is explored through different experiences and ways of listening: by doing sound-walks and performative interventions, and by recording sounds that are sometimes (in)audible to human ears. The sounds, generated by people and machines in the tunnel, were recorded using ambient microphones, homemade contact microphones and electromagnetic antennas, and a hydrophone, making audible the hidden ‘voices’ from the mechanical sounds and the resonating space. The activities of workers, visitors and machines are acoustically affected (filtered) and amplified by the architecture and the landscape. This sound-space was perceived as a sound-being in constant and subtle metamorphosis.