The great churches of Kievan 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 Kievan state, which quickly established itself, was strongly influenced by Byzantine architecture. 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 what the pagan Slavic temples should have looked like. The 10th-century Church of the Tithes in Kiev was the first cult building to be made of stone. The earliest Kievan churches were built and decorated with frescoes and mosaics by Byzantine masters.