ROME — For archaeologists, the excavation of Rome’s newest subway line has been the gift that keeps on giving.

Two years after a second-century military barracks was found during the excavation of the Amba Aradam station, archaeologists last week presented the remains of a richly decorated domus, or house, that they believe belonged to the commander of the military post.

Even after the discovery of the military complex, “we didn’t imagine that we’d find a house with a central courtyard,” a fountain and at least 14 rooms, said Simona Morretta, the state archaeologist responsible for the site. One of the rooms appears to have been heated.