SOFIA, BULGARIA—A basilica said to date to the era of Constantine the Great (A.D. 306 to 337) has been unearthed near the West Gate of ancient Serdica, now modern Sofia, Bulgaria. The basilica was adorned with mosaics, but further excavation of the building may not be possible because of its location. A second-century Roman wall, a fifth-century gate, and a sixth-century tower have also been found at the site, which will become a public park.