About 3,500 years ago, when the Bronze Age was ending in Europe and the Olmec civilization was thriving in Mexico, natives in San Antonio were living off the land using primitive tools, as they had been for thousands of years.

Signs of ancient human settlements have been found elsewhere in Texas, some more than 10,000 years old. And now there's evidence that about 1500 B.C. — three millennia before the Spanish Conquest — natives were building structures along the San Antonio River.

Last month, workers preparing Mission County Park for construction found evidence of one such building while searching for a previous location of nearby Mission San Jose, which they never located.

What they did uncover — and then reburied after preliminary investigation — were remains of a prehistoric hut that burned down but left significant clues....