Photo of Ruins, how to Paint it as if it is in original Time period
I can tell you with certainty that architecture like this does exist, is still being built and is pretty common in Europe, for example in Halle or Leipzig, Germany. You can also see examples of it in Normandy (France). 

The technique of mortaring brick and coating it with cement or mud is pretty common. I imagine the biggest problem you will have is finding out the color used at the time. In order to keep buildings cool, the southern walls would usually have a light color - as white (a so-called lime wash) was easy to produce - I would go for that, unless someone with more experience in Indian architecture can add their knowledge...