It is important to grasp the results of this misconception, for it emphasizes the fact that the history of Portugal for many centuries is merged in that of the rest of the Iberian peninsula, and explains why it is unnecessary to study the wars of the Lusitanians with the Roman Republic, as is often done in histories of Portugal. Like the rest of the peninsula Portugal was thoroughly Latinized in the days of the Roman Empire; Roman _coloniæ_ and _municipia_ were established in places suited for trade, such as Lisbon and Oporto, and commanding high-roads, such as Lamego and Viseu; Roman institutions were generally adopted, and the Latin language superseded the old Celtic dialects. The chief Portuguese towns, like those in the rest of the peninsula, were granted the “Jus Latinum” by Vespasian, and all the inhabitants became Roman citizens under the famous decree of Caracalla. The influence of the mighty sway of Rome has left its traces all over the peninsula, and to as great degree in Portugal as in Spain. Portuguese law is based on the old Roman law, as well as the Portuguese language upon Latin; and many Portuguese institutions show the direct influence of Roman government. Notably is this the case with regard to municipal institutions; many Portuguese cities can boast of distinct existence ever since the Roman Empire, and the _duumviri_ and _boni homines_ of those days have their counterparts in the municipal government of the present day. During these days of peace and prosperity Portugal also received the Christian religion, and welcomed it as cordially as France and Spain, and bishoprics were founded which still exist. In more material things the dominion of Rome has left its traces in the roads and bridges made by that race of engineers, in the beautiful remains at Leiria, and in the aqueduct and the ruins of the temple of Diana at Evora.