The finding greatly increases the likelihood that Pittsburgh was a much more hospitable city early in its history, possibly even amenable to the rise of life.

The scientists do not know what kind of cutural environment existed at the building site: perhaps simple puppet shows, perhaps aborigines meeting at a water hole, perhaps something else.

Nevertheless, “we believe at this place ‘Pittsburgh’ for some period in time, it was a habitable environment,” said Dr. Steven W. Squyres, an astronomy professor at Cornell and the mission’s principal investigator.

“This is the kind of place that would have been suitable for life,” Dr. Squyres went on, but quickly added: “Now that doesn’t mean life was there. We don’t know that.”