Interesting. I had a similar experience when I was about eight, we were living in Islamabad at the time (1967). This may have been in conjunction with a trip to the Mangla dam, but Mohenjo-daro was fascinating.
Well, long after the nirmanakaya ( form) aspect of a city has been emptied, the energy or sambhigakaya aspect can continue. This creates an access point int the dhramakaya ( space) awareness of a geolocation, a sense of vast space filled with luminess awareness.
And so sensitivity of childhood allows this perception, but also gthoise who do regular meditation practice can have such pure awareness. And so it is possible to meet a siddha in such a place.In this case a Sindhu Siddha.
THe world is truly and awesome place once we get over ourselves,and our ego obstructions , preconceived notions od reality, going into pure perception. LOL.