A mixed style, i.e. a style composed of Graeco-Roman and Oriental elements which, in earlier centuries, cannot be clearly separated. The form of the church used most in the west, a nave supported on columns and an atrium (see BASILICA), appears in many examples of the fifth century in Byzantium as well as in Rome; the sixth century saw such churches erected in other regions outside Rome, at Ravenna, in Istria, and in Africa. In the West this style of building occasionally presents (in S. Lorenzo and S. Agnes at Rome) peculiarities which are ascribed by some authorities to Oriental origin -- galleries over the side aisles, spirally channelled columns, and imposts between capitals and arches. Vaulted basilicas are to be found at an early date in Asia Minor, Syria, Africa and also at Constantinople. But the early Etruscans and Romans were skilful in the art of constructing vaults, even before that time; for instance, the basilica of Constantine. The domi...