Semenjak permulaan abad ke-3, keadaan mulai berubah. "[[Krisis Abad Ketiga|Kemelut Abad Ketiga]]" menyifatkan bencana-bencana dan gejolak-gejolak political yang melanda Kekaisaran Romawi yang sudah berada di ambang kehancuran.<!-- Keresahan Theakibat newdibayang-bayangi feelingancaman ofinvasi dangerbangsa andbarbar theterlihat menacejelas ofpada barbariankeputusan invasions was clearly shown by the decision of EmperorKaisar [[AurelianAurelianus]],whountuk atmemagari yearibukota 273 finished encircling the capital itself with a massivedengan [[AurelianTembok WallsAurelianus|walltembok]] whichraksasa hadsepanjang a perimeter that measured close tohampir {{convert|20|km|0|abbr=on|lk=off}} yang rampung dikerjakan pada tahun 273.<!-- Rome formally remained capital of the [[Roman Empire|empire]], but emperors spent less and less time there. At the end of 3rd century [[Diocletian]]'s political reforms, Rome was deprived of its traditional role of administrative capital of the Empire. Later, [[Western Roman Empire|western emperors]] ruled from [[Milan]] or [[Ravenna]], or cities in [[Gaul]]. In 330, [[Constantine I]] established a second capital at [[Constantinople]].
