The architectural feature of the Islamic artists that came from the Romans was the horseshoe arch. This is what they liked best in Roman culture, so they decided to use it in their art and architecture as well. Islamic architecture is quite different from any other, although it was certainly influenced by many other world architectures.
Most likely harmony, the degree to which a person appreciates the harmony depends on various things such as: their level of musical training, their ear, and again just their opinion.<span />