Selvanathan and other sthapatis continue to use the simple tools of their predecessors, such as wooden hammers and thread dipped in a red oxide dye to measure dimensions, also laid out by the Vastu Shastra. “Every structure we build has a grammar. If we don’t adhere to those rules based on ancient wisdom, we will not be healthy people,” says Ponni Selvanathan, the sthapati’s wife and also a member of the family business.

Whether that business continues, welcoming a 39th generation into the trade, remains to be seen, says Selvanathan with a knowing smile. His older son, he says, has recently shown interest. “He’s learning the ropes. Only time will tell.”

*Correction: This article previously stated that Chithra Madhavan was affiliated with Krea University. She is an independent historian.