Between 5th century and 11th century, the cities of the western half of the Roman Empire underwent invasions, famines, plagues and economic hardship.The churches, hospitals, monasteries and castles built all over the Europe after the millennium represented an optimistic architectural expression of a progressive social order.Christian monasteries be left the most inspired expression of European. It became more important and designed like a city.in the Byzantine sources, the marble columns in the upper galleries, spolia dragged across Europe form Roman sites, reached up directly into the intrados of the arches without a mediating turntable. This contradicted both the structural and grammatical logic of columns and arches.Charlemagne’s palace is buily with multi-cultural architectural styles.For instance, the court borrowed from Byzantine and palace organization was taken from Constantine. Columns and arches are similitaries between  Great Mosque of Cordoba and Christian architecture. The designers pursued a local interpretation of a well-known Roman precedent, using three arches flanked with classical half columns capped with an attic story with pilasters.