In secular buildings this plan was more typically used for the smaller audience halls of the emperors, governors, and the very rich than for the great public basilicas functioning as law courts and other public purposes. This was the normal pattern used for Roman churches, and generally in the Western Empire, but the Eastern Empire, and Roman Africa, were more adventurous, and their models were sometimes copied in the West, for example in Milan. All variations allowed natural light from windows high in the walls, a departure from the windowless sanctuaries of the temples of most previous religions, and this has remained a consistent feature of Christian church architecture. Formulas giving churches with a large central area were to become preferred in Byzantine architecture, which developed styles of basilica with a dome early on. A particular and short-lived type of building, using the same basilican form, was the funerary hall, which was not a normal church, though the surviving examples long ago became regular churches, and they always offered funeral and memorial services, but a building erected in the Constantinian period as an indoor cemetery on a site connected with early Christian martyrs, such as a catacomb. The six examples built by Constantine outside the walls of Rome are: Old Saint Peter's Basilica, the older basilica dedicated to Saint Agnes of which Santa Costanza is now the only remaining element, San Sebastiano fuori le mura, San Lorenzo fuori le Mura, Santi Marcellino e Pietro al Laterano, and one in the modern park of Villa Gordiani. A martyrium was a building erected on a spot with particular significance, often over the burial of a martyr. No particular architectural form was associated with the type, and they were often small. Many became churches, or chapels in larger churches erected adjoining them. With baptistries and mausolea, their often smaller size and different function made martyria suitable for architectural experimentation. Among the key buildings, not all surviving in their original form, are:  With the final legalization of Christianity, the existing styles of Christian art continued to develop, and take on a more monumental and iconic character. Before long very large Christian churches began to be constructed, and the majority of the rich elite adapted Christianity, and public and elite Christian art became grander to suit the new spaces and clients. Although borrowings of motifs such as the Virgin and Child from pagan religious art had been pointed out as far back as the Protestant Reformation, when John Calvin and his followers gleefully used them as a stick with which to beat all Christian art, the belief of André Grabar, Andreas Alföldi, Ernst Kantorowicz and other early 20th-century art historians that Roman Imperial imagery was a much more significant influence "has become universally accepted".