The great churches of the Rus', built after the adoption of Christianity in 988, were the first examples of monumental architecture in the East Slavic lands. The architectural style of the Kyivan state was strongly influenced by the Byzantine. Early Eastern Orthodox churches were mainly made of wood, with the simplest form of church becoming known as a cell church. Major cathedrals often featured scores of small domes, which led some art historians to take this as an indication of the appearance of pre-Christian pagan Slavic temples.