The disorganization in the Roman empire, which led to its fall, allowed the conquest by the Visigoths and the Christian Suevi in later years, along with other Germanic tribes. Many of the structures that survived this period include ancient churches and inscriptions built over previous constructions, which were the centre of Lusitanian settlements. Early Christian influences persisted for several centuries, until the Moors and Arab Berber peoples (from North Africa) invaded the Peninsula, including all of the territory which would eventually become Portugal. The Moors were first to construct many of the medieval castles that dot the landscapes of Portugal. From the northern enclaves (Galicia and Asturias in Portugal's case), the Christian Reconquista began, expanding progressively south towards the southern coast of the Iberian Peninsula. This was not a permanent expansion, since the Moorish-Christian frontier continued to expand and retract for several years, with the victories and defeats of each battle. Meanwhile, Portugal became a county of the Kingdom of León and briefly during the independence of the Kingdom of Galicia in the 1060s and 1070s. It became an autonomous dominion of the Kingdom of León in 1128, emerging as a fully independent kingdom in 1139, officially recognized by the Treaty of Zamora in 1143. After this period, and with the rise of the Portuguese state after the beginning of the Age of Discovery, Portuguese architecture expanded under the patronage of the wealthy kings, nobility, powerful clergy and through the many battles with rivals such as Castile, the French and Dutch. During these periods, many of the prominent buildings were destroyed, rebuilt, re-purposed and closed on the whims of the monarchy, which progressively used architectural projects to support their power, remember past glories or expand their position in the Iberian peninsula. With the demise of the powerful clergy and religious orders, and eventually the fall of the monarchy in Portugal, many of the once important buildings in the country were either reused as seats of governmental power, abandoned into ruin or reused as museum, although some remained places of public use (such as the religious places of worship). The 20th century movement to restore and preserve the architectural history of Portugal was initiated under the "Direcção Geral dos Edifícios e Monumentos Nacionais (DGMEN)" during the Estado Novo regime in order to inventory national treasures and preserve existing monuments. Although there are numerous monuments from various ages some of them have a special value due to their historical, architectural, artistic and cultural importance.