When we hear the words "architectural terracotta" we think of decorations, fancy classical or art deco statuary or strong and durable yet mass produced weather proof wall claddings, but there is also structural terracotta: most famously used in vaulting or as stairs. Thin terracotta tiles are set on brackets or vertical load bearing walls with fast curing gypsum plaster (exactly that which you used as a kid to cast little statues), where it can nearly instantly bear its own weight. Builders work fast right out in the air with at most simple guiding forms or lines but usually freehand, until they have completed the vault. Almost simultaneously another layer of tiles are set in cement or lime mortar on top of the first, and then usually a third. Now the vault is strong enough to carry itself, a stair, or insulation etc. In the US this is often called Gustavino Vaulting.
https://hell.twtr.plus/media/1b00f934cd612861f82fcc26e290dbf74916debaccfe669683a5b3c6742b2b75.file
https://hell.twtr.plus/media/9efd1d54a84df099f82544bf5b220e49f1ca0441bf528856da13ca33bee59c90.file
https://hell.twtr.plus/media/06c99d7d4bb6e5dd6fd76d47c6b9999d3525a4fe3b336c1a577bb6cfb71a114c.file
https://hell.twtr.plus/media/193eb1e9769f555d2acae4f80b9a3adada90117b316673e17bbf84b73bef8c3e.file