Complex sentence: It has been suggested that many of the cathedrals and intricate sculptured gothic buildings that have been chromolithed, were originally painted by their architects so Warrener's work can be seen as a revalorisation of heritage buildings.
Split into simpler sentences: It has been suggested that many of the cathedrals and intricate sculptured gothic buildings that have been chromolithed, were originally painted by their architects. As a result, Warrener's work can be seen as a revalorisation of heritage buildings.