A visit to the Indian temple where "0" was invented

The BBC's Alex Bellos travels to Gwalior, an Indian city that contains a temple with the oldest known use of the number "0". It's part of an effort to figure out why zero would appear in India, and not in other, earlier civilizations that were mathematically adept. From Bellos' perspective, part of the answer might lie in theology — a mathematical representation of the mystical idea of "nothingness".