The Roman Empire (27 BCE – 476 CE) was one of the largest and most influential empires in history. At its peak under Emperor Trajan (117 CE), Rome controlled territory spanning from Britain to Mesopotamia. Roman contributions include republican and imperial governance systems, Latin language (ancestor of Romance languages), Roman law (foundation of modern legal systems), concrete architecture (Colosseum, Pantheon, aqueducts), roads spanning 400,000 km, and Christianity's eventual adoption as state religion. The Western Empire fell in 476 CE, while the Eastern (Byzantine) Empire continued until 1453 CE.