150px|Objects found excavating the remains of Dorestad. The northern border of the Roman Empire  was set at the Rhine in 47 AD. The border was protected with fortresses and the Low Countries became the outer provinces of the empire, situated near the Roman-Germanic border. Probably because of the (founded) fear of Germanic incursions, Roman settlements (such as Roman villas and colonies) were extremely sparse, and Roman presence was mainly limited to three Castra (Noviomagus, near modern Nijmegen; Flevum, near Velsen; and a last one near Oudenburg, its name is unknown), and a set of Castellum (of which Castellum Trajectum would later become Utrecht). These together formed the only population centers which surpassed the native villages of the time in terms of architecture and, in some cases, population. The only possible exception was the city of Atuatuca Tungrorum, which later became one of the earliest centers of Christianity in the Low Countries. Around the (ruins) of these Castra and Castellum that the first large settlements arose. Very little is known about these settlements, apart from archeological material, as there was little literacy at the time. Based on archeological evidence, together with sparsely preserved written text it is thought that Dorestad (build near the former Roman fortifications) was the most populous and important settlement of the region; with an estimated 3,000 inhabitants, it was much larger than the remaining villages, which often had no more than 100–150 inhabitants. Dorestad seems to have been the principal trading center of the Low Countries from around 600 CE until it started to decline around the early 9th century, caused by frequent Viking raids, Frisian-Frankish wars, silting of its river connection and the emerging of new centers favoured by the Franks, such as Liège, Cambrai, Soissons, Herstal, Tournai and, most to the north, the neighbouring site of Nijmegen   .
150px|Objects found excavating the remains of Dorestad. The northern border of the Roman Empire , known as Limes, was set at the Rhine in 47 AD. The border was protected with fortresses and the Low Countries became the outer provinces of the empire, situated near the Roman-Germanic border. Probably because of the (founded) fear of Germanic incursions, Roman settlements (such as Roman villas and colonies) were extremely sparse, and Roman presence was mainly limited to three Castra (Noviomagus, near modern Nijmegen; Flevum, near Velsen; and a last one near Oudenburg, its name is unknown), and a set of Castellum (of which Castellum Trajectum would lay the foundation of Utrecht). These together formed the only population centers which surpassed the native villages of the time in terms of architecture and, in some cases, population. The only possible exception was the city of Atuatuca Tungrorum, which later became one of the earliest centers of Christianity in the Low Countries. Around the (ruins) of these Castra and Castellum the first large settlements arose. Very little is known about these settlements, apart from archeological material, as there was little literacy at the time. Based on archeological evidence, together with sparsely preserved written text it is thought that Dorestad (build near the former Roman fortifications) was the most populous and important settlement of the region; with an estimated 3,000 inhabitants, it was much larger than the remaining villages, which often had no more than 100–150 inhabitants. Dorestad seems to have been the principal trading center of the Low Countries from around 600 CE until it started to decline around the early 9th century, caused by frequent Viking raids, Frisian-Frankish wars, silting of its river connection and the emerging of new centers favoured by the Franks, such as Liège, Cambrai, Soissons, Herstal, Tournai and, most to the north, the neighbouring site of Nijmegen . In 696, Willibrord, an Anglo-Saxon missionary. was permitted by the Frankish king Pippin II to settle in Utrecht and initiated by Pop Sergius I as archbishop of the Frisians. He buit in Utrecht a church dedicated to St. Martin and from there he converted the Frisians to Christianity, sparking the city to become a major ecclesiastical center in the Low Countries .
A
, known as Limes,
R
later become
lay the foundation of
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that
A
.
A
In 696, Willibrord, an Anglo-Saxon missionary. was permitted by the Frankish king Pippin II to settle in Utrecht and initiated by Pop Sergius I as archbishop of the Frisians. He buit in Utrecht a church dedicated to St. Martin and from there he converted the Frisians to Christianity, sparking the city to become a major ecclesiastical center in the Low Countries