罗马共和国与罗马帝国(Roman republic and empire)
曾统治西方世界的古国。西元前509年以罗马城为中心建立共和国，西元前27年创建罗马帝国，直至西元5世纪西罗马帝国最後瓦解。共和国政府由两名执政官、元老院、地方长官（最初全是贵族），以及两个一般的平民议会（军事百人团大会和平民部族大会）组成。西元前451年颁布的成文法典十二铜表法，成为了罗马私法的基础。到西元前3世纪末，整个义大利都属於罗马版图。到西元前3世纪末，罗马领土包括了整个义大利；至共和国後期，其版图包括西欧大部分、北非以及近东地区，并将这些领土划分为行省。凯撒是在经过一段时期的内战後，以独裁者身分掌管国家大权。他遭暗杀（西元前44年）後，安东尼、雷比达和屋大维之间发生冲突，最终屋大维获胜（西元前31年），即位为皇帝，称奥古斯都（西元前27～西元14年在位）。帝国政府（元首统治）结合了共和政体和君主政体。395年帝国分裂为东西两部分，西罗马帝国受到来自野蛮民族的严重侵略，罗马於476年遭日耳曼人入侵；东罗马帝国则继续存在，称为拜占庭帝国，一直存续到整个中世纪时期。
English version：
Roman republic and empire
Ancient state that once ruled the Western world. It centered on the city of Rome from the founding of the republic (509 BC) through the establishment of the empire (27 BC) to the final eclipse of the empire of the West (5th century AD). The republic's government consisted of two consuls, the Senate, and magistrates, originally all patricians, and two popular plebeian assemblies: the military centuriate assembly and the civilian tribal assembly. A written code, the Law of the Twelve Tables (451 BC), became the basis of Roman private law. By the end of the 3rd century BC, Roman territory included all of Italy; by the late republican period it encompassed most of western Europe, northern Africa, and the Near East, organized into provinces. After a period of civil war, Julius Caesar took power as dictator. Following his assassination (44 BC), conflict among Mark Antony, Lepidus, and Octavian resulted in Octavian's victory (31) and his accession as emperor Augustus (r.27 BC-AD 14). The imperial government, a principate, combined aspects of the republic and a monarchy. In AD 395 the empire split into eastern and western halves, with the west under severe pressure from barbarians. Rome fell to German invaders in 476; the east continued as the Byzantine empire through the Middle Ages.