I mentioned earlier there was widespread church construction occurring at this time. Christians borrowed from Roman basilica designs to create their churches, designed to fit a large number of church-goers. A Campanile (a freestanding bell tower) and Westworks (towers framing the end of a church) were added to the design. Exteriors were plain (contrary to when we get to Gothic architecture), and the focus on these early Christian churches was the interior. Interiors were designed for dramatic effect, to bring a sense of awe to worshippers—in fact, a nickname for churches built at this time was "Houses of Mystery." The church builders put in mosaics, which were decorations made with small pieces of glass and stone set in cement. The mosaics themselves were like visual sermons, complete with symbols for Christ's majesty and goodness, for viewers to admire when they were not looking at the priest. Many of the mosaics were placed next to flickering candles, the light of which would cause them to glow. "Houses of Mystery."