Keystone
Key-stone.
The key stone is the stone placed at the apex of the arch, and prevents the two sides of the arch falling in and collapsing.
the key stone is the stone that is at the top of an arch. It is this stone that absorbs the majority of the forces stabilizing the arch formed
Compression
It is the keystone.
I know that the top stone, is called a Key stone.
The Roman arch is said to have been built by Archimedes of Sicily. Roman arches provided the ideal conditions for building beautiful and lofty architectural buildings as against stone bricks.
Stone and clay was used and packed to form the arch of Augustus. Their were two.
The wedge-shaped stone in an arch that causes the rocks to lock together is called a keystone. It is positioned at the top center of the arch and helps distribute the weight evenly across the stones, ensuring the stability and strength of the arch.
The keystone
The final stone placed in the arch is known as the keystone. It is wedge-shaped and sits at the very top, locking all the other stones in place to evenly distribute the weight and provide stability to the arch structure.
The two materials that always here with arch brides is stone or brick. There are plenty more though.