My family and I visited the Greek island of Kos last month and during my time on the Island I was fortunate to visit the archaeological remains from different periods in history whilst learning about the ancient city that was once there. Hippocrates, the great Physician, was born on the island where he founded a school of medicine in the 5th century. The most interesting part for me was visiting the Roman Odeum, and in particular the (postscaenium) Skene, which is a multi-story building and where the dressing rooms would have been. There is evidence of how the interior walls would have been decorated, just beautiful!
Ancient Romans decorated the interior walls of their houses and buildings with paintings executed on wet plaster, a technique known as fresco (meaning on fresh plaster). On to the surface of the wall they applied a rough coat of mortar, this was often three layers thick and composed of slaked lime and coarse sand. The surface was then made smooth and ready to take paint by polishing the surface with glass, marble and cloth. The drawings were then outlined using fine incisions to guide the artists and then fresco was painted using bold primary colours. (rsc.org)
Fig.1 to Fig.4 My own photographs of a Roman Odeum, Kos