Our church windows may have been rumored to be melting, which you may have heard at museum visits. This is a persistent myth, as glass is actually not a liquid. In order to transform it to a liquid, you would need to reach extremely hot temperatures. However, glass is an amorphous solid, which is a mixture between a liquid and a solid. This is not why the church windows have heavy bottoms; it is due to the manufacturing techniques used centuries ago, when glass techniques weren’t perfect. If a window ended up with a heavy side, it was simply placed on the bottom.