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Legacy

As the Western Roman Empire crumbled, the new Germanic rulers who conquered its constituent provinces maintained most Roman laws and traditions. Many of the invading Germanic tribes were already Christianized, although most were followers of Arianism. They quickly changed their adherence to the state church of the Roman Empire. This helped cement the loyalty of the local Roman populations, as well as the support of the powerful Bishop of Rome. Although they initially continued to recognize indigenous tribal laws, they were more influenced by Roman law and gradually incorporated it. Roman law, particularly the Corpus Juris Civilis collected on the orders of Justinian I, is the basis of modern civil law. In contrast, common law is based on Germanic Anglo-Saxon law. Civil law is by far the most widespread system of law in the world, in force in some form in about 150 countries.

Latin as a language did not disappear. Vulgar Latin combined with neighboring Germanic and Celtic languages, giving rise to modern Romance languages such as Italian, French, Spanish, Portuguese, Romanian, and a large number of minor languages and dialects. Today, more than 900 million people are native speakers of Romance languages worldwide. In addition, many Romance languages are used as lingua francas by non-native speakers.

Latin also influenced Germanic languages such as English and German. It survives in a "purer" form as the language of the Catholic Church; the Catholic Mass was spoken exclusively in Latin until 1969. As such it was also used as a lingua franca by ecclesiasticals. It remained the language of medicine, law, and diplomacy, as well as of intellectuals and scholarship, well into the 18th century. Since then the use of Latin has declined with the growth of other lingua francas, especially English and French. The Latin alphabet was expanded due to the split of I into I and J, and of V into U, V, and, in places (especially Germanic languages and Polish), W. Latin script is the basis for the largest number of alphabets of any writing system and is the most widely adopted writing system in the world. Roman numerals continue to be used in some fields and situations, though they have largely been replaced by Arabic numerals.

A very visible legacy of the Western Roman Empire is the Catholic Church. Church institutions slowly began to replace Roman ones in the West, even helping to negotiate the safety of Rome during the late 5th century. As Rome was invaded by Germanic tribes, many assimilated, and by the middle of the medieval period (c. 9th and 10th centuries) the central, western, and northern parts of Europe had been largely converted to Roman Catholicism and acknowledged the Pope as the Vicar of Christ. The first of the Barbarian kings to convert to the Church of Rome was Clovis I of the Franks; other kingdoms, such as the Visigoths, later followed suit to garner favor with the papacy.

When Pope Leo III crowned Charlemagne as "Roman Emperor" in 800, he both severed ties with the outraged Eastern Empire and established the precedent that no man in Western Europe would be emperor without a papal coronation. Although the power the Pope wielded changed significantly throughout the subsequent periods, the office itself has remained as the head of the Catholic Church and the head of state of the Vatican City. The Pope has consistently held the title of "Pontifex Maximus" since before the fall of the Western Roman Empire and retains it to this day; this title formerly used by the high priest of the Roman polytheistic religion, one of whom was Julius Caesar.

The Roman Senate survived the initial collapse of the Western Roman Empire. Its authority increased under the rule of Odoacer and later the Ostrogoths, evident by the Senate in 498 managing to install Symmachus as pope despite both Theodoric of Italy and Emperor Anastasius supporting another candidate, Laurentius. Exactly when the senate disappeared is unclear, but the institution is known to have survived at least into the 6th century, inasmuch as gifts from the senate were received by Emperor Tiberius II in 578 and 580. The traditional senate building, Curia Julia, was rebuilt into a church under Pope Honorius I in 630, probably with permission from the Eastern emperor, Heraclius.