Most scholars agree that Christ probably wasn’t born on December 25th — and possibly not even in the winter. Now a historian has put forth an intriguing theory about the first December 25 Christmas:

The church where the tradition of celebrating Christmas on Dec. 25 may have begun was built near a pagan shrine as part of an effort to spread Christianity, a leading Italian scholar says.

Italian archaeologists last month unveiled an underground grotto that they believe ancient Romans revered as the place where a wolf nursed Rome’s legendary founder Romulus and his twin brother Remus.

A few feet from the grotto, or ”Lupercale,” the Emperor Constantine built the Basilica of St. Anastasia, where some believe Christmas was first celebrated on Dec. 25.

Constantine ended the frequent waves of anti-Christian persecutions in the Roman empire by making Christianity a lawful religion in 313. He played a key role in unifying the beliefs and practices of the early followers of Jesus.

In 325, he convened the Council of Nicaea, which fixed the dates of important Christian festivals. It opted to mark Christmas, then celebrated at varying dates, on Dec. 25 to coincide with the Roman festival celebrating the birth of the sun god, Andrea Carandini, a professor of archaeology at Rome’s La Sapienza University, told reporters Friday.

The Basilica of St. Anastasia was built as soon as a year after the Nicaean Council. It probably was where Christmas was first marked on Dec. 25, part of broader efforts to link pagan practices to Christian celebrations in the early days of the new religion, Carandini said.

”The church was built to Christianize these pagan places of worship,” he said. ”It was normal to put a church near these places to try to ‘save’ them.”

Rome’s archaeological superintendent Angelo Bottini, who did not take part in Carandini’s research, said that hypothesis was ”evocative and coherent” and ”helps us understand the mechanisms of the passage from paganism to Christianity.”

Bottini and Carandini both said future digs could bolster the link between the shrine and the church if structures belonging to the ”Lupercale” are found directly below the basilica.

The Basilica St. Anastasia was the first church to rise not on the ancient city’s outskirts, but on the Palatine Hill, the palatial center of power and religion in imperial Rome, Carandini said. Though little known today, at the time of Constantine it was one of the most important basilicas for Christians in Rome, he said.

The ”Lupercale” shrine — named after the ”lupa,” Latin for she-wolf — is 52 feet below ground. So far, archaeologists have only been able to see it by inserting probes and cameras that have revealed a vaulted ceiling decorated with colored marble and a white imperial eagle.