The Tank

https://tanksounds.org
Constructed around 1940 as a railroad water-treatment facility, the Tank was moved by a utility company to Rangely in the mid-1960s for use as part of a fire-suppression system. The plan was never realized, as the underlying shale proved unable to support the weight of the filled tank. However, the bed of gravel upon which the tank was placed bowed its floor into a gentle parabola, giving it its remarkable acoustical resonance.

A Water Tower Turned Tuning Tower by Alex Ross, The New Yorker, July 24, 2017