A CASCADE CATHEDRAL is a human cathedral that has been plumbed.
Water is lifted to the towers and let fall: down the buttresses, out through the rose window, along flumes bolted to the nave, into a warm floor two hand-spans deep where the whole colony gathers.
Requires a BREEDING SHRINE.
The Olvir did not raise these. They found them: tall, dry, acoustically magnificent buildings that the locals had abandoned or ceded, and could not imagine a use for that did not involve sitting still.
The refit takes a generation. The stonework is untouched — it is considered impolite — and the congregation is simply moved from the pews to the water.
Human opinion remains divided.