Monolithic church
A monolithic church or rock-hewn church is a church made from a single block of stone. Because freestanding rocks of sufficient size are rare, such edifices are usually hewn into the ground or into the side of a hill or mountain. They can be of comparable architectural complexity to constructed buildings. The term "monolithic church" is used of churches in various countries, not least the complex of eleven churches in Lalibela, Ethiopia, believed to have been created in the 12th century. Ethiopia. The eleven monolithic churches in Lalibela are: The most famous of the edifices is the  cross-shaped Church of St. George. Tradition credits its construction to the Zagwe dynasty King Gebre Mesqel Lalibela, who was a devout Orthodox Tewahedo Christian. The medieval monolithic churches of this 12th-century 'New Jerusalem' are situated in a mountainous region in the heart of Ethiopia near a traditional village. Lalibela is an important center of Ethiopian Christianity, and even today is a place of pilgrimage and devotion. Lalibela is one of the world's heritage sites registered by UNESCO. Many other churches were hewn from rock in Ethiopia, outside of Lalibela in Amhara Region. This practice was very common  in Tigray, where the outside world knew of only a few such churches until the Catholic priest Abba Tewelde Medhin Josief presented a paper to the Third International Conference of Ethiopian Studies in which he announced the existence of over 120 churches, 90 of which were still in use. Despite Dr. Josief's death soon after his presentation, research over the next few years raised the total number of these rock-hewn churches to 153, particularly in the districts Kola Tembien, Degua Tembien, Hawzen and Sa'esa Tsada Amba. Their precise ages are not well defined but the majority were probably  carved during the reigns of the emperors Dawit II (ca. 1380–1413 CE) and Zer’a Ya’iqob (1434–1468), and some possibly earlier when Anbessa Wudim (legendary date: 10th C.) or Yekuno Amlak (1270–1285) were in power. According to local belief excavation of the churches was started by a group of missionaries known as the ‘Nine Saints’, who arrived in Ethiopia from the Mediterranean region during the fifth or sixth century. Together with their Ethiopian followers these missionaries inspired a long tradition of monasticism, promoting isolation in remote and highly inaccessible locations such as those in which the rock-hewn churches are found . Preferred lithologies for church hewing were Adigrat Sandstone and Enticho Sandstone. The tradition continues up to the present, as rock-hewn churches are still being excavated today. Although the churches differ in design and structure, most consist basically of halls with a basilica architecture that includes three naves and a vestibule, pillars, vast ceilings, archways, and domes. Walls and ceilings are often decorated with rock carvings and colourful frescoes. Many of the medieval churches are still used today for Christian orthodox religious ceremonies and festivities. Other churches. There are a number of monolithic churches elsewhere in the world. However, none  have the free-standing external walls of the Lalibela churches. They instead more closely resemble cave monasteries in that they consist of tunnels converging into a single rock. Examples include: