The scientists found such paintings and signs of a regal two-story mausoleum, bolstering their conviction that the ancient Jewish monarch was buried there.
Ehud Netzer, head of Jerusalem's Hebrew University excavation team, which uncovered the site of the king's winter palace in the Judean desert in 2007, said the latest finds show work and funding fit for a king.
"What we found here, spread all around, are architectural fragments that enable us to restore a monument of 25 meters high, 75 feet high, very elegant, which fits Herod's taste and status," he told The Associated Press in an interview at the hillside dig in an Israeli-controlled part of the West Bank, south of Jerusalem.
No human remains or inscriptions have been found to prove conclusively that the tomb was Herod's, but excavation continues.
Herod is known for extensive building throughout the Holy Land.
Netzer said that since finding fragments of one ornately carved sarcophagus in 2007, he and his team have found two more, suggesting the monumental tomb may have been a royal family vault.
"A mausoleum like the one which we have here was generally built by a king but not (necessarily) only for himself, many times for his children and his family, like the famous mausoleum of Augustus in Rome, of Hadrian in Rome," he said. "It's not a surprise that we found here more than one sarcophagus."
Herod was the Jewish proxy ruler of the Holy Land under imperial Roman occupation from 37 B.C. and reigned for more than six decades. He is known to have had a taste for extravagance.
In Herod's private box at the auditorium, diggers discovered delicate frescoes depicting windows opening on to painted landscapes, one of which shows what appears to be a southern Italian farm, said Roi Porat, one of Netzer's assistants on the digs. Just visible in the paintings, dating between 15 and 10 B.C., are a dog, bushes and what looks like a country villa.
Site surveyor Rachel Chachy-Laureys said the paintings were executed using techniques unknown in the Holy Land at the time and must have been done by artisans imported from Rome.
"There has been no other discovery of this type of painting in the Middle East, as far as we know, until now", she said.
Gidon Foerster, a professor of archaeology at the Hebrew University not connected with this dig, agreed that the art is "unique" for the region. "King Herod is said to have been buried there and this proves it as much as it can possibly be proved," he said.
The Herod of Christian tradition was a bloodthirsty megalomanic, who flew into a frenzy when he met the three wise men on the way to Bethlehem carrying gifts for the baby Jesus and telling of the birth of a new king of Israel.
Herod purportedly ordered the slaying of all children in his realm younger than 2. But historians are not convinced of the story's accuracy.
After Herod's death in the 1st century B.C., Herodium became a stronghold for Jewish rebels fighting Roman occupation, and the palace site suffered significant battle damage before it was destroyed by Roman soldiers in A.D. 71, a year after they razed the Second Temple in Jerusalem.
The insurgents reviled the memory of Herod as a Roman puppet, and Netzer and his team believe that the violence inflicted on the first stone casket they found suggests the rebels knew it held the king's bones.
"That sarcophagus was found shattered all over the place. It seems it was taken from its place and was destroyed in a fit of rage," Porat said. "That, among other things, is what tells us it was the sarcophagus of Herod."