During a rainy day, I found myself waiting for the N train at 62nd street. As I was looking around, I saw colums being connected by voussoirs. Unlike the Romans, these voussoirs did not have a keystone but just a wide semicircle that connects each columns. “Tudor arch” is what they call this wide arch. Back then, the material made for voussoirs were stones because it was an easy material to find. Now, we use cement which holds the shape of a semicircle without a keystone. As you can see, there is no keystone in this voussoirs which shows advancement in material and form of architecture. It doesn’t have a different function because it’s supposed to hold up the colums just like the Romans. However nowadays you see less often the use of voussoirs because we use plain platforms to hold bug buildings. There are many buildings which incorporates such arches such as the navel in the Santa Sabina and the window which are carved as a voussoirs.