The original Castle of Angers had its first large settlement in the 1st century A., although it had possibly been constructed in an earlier time period. The development of the town of Angers was very closely related to the castle's development. When the castle was first built, the town of Angers was in a period of great expansion. It was one of the cities which linked the other important cities of Gallo-Roman times. When in the 3rd and 4th centuries Angers began to be in need of defense, a walled city was built leaving many of Angers' main buildings outside. This included many of its cathedrals and other religious establishments. The wall around the city had round towers and four gates, making it a defensive wall. This was the first defense of Angers. .
In the 9th century, the Norsemen invaded the county of Anjou driving many of the people of Angers out of their own city. Charles the Bald later drove out the Norsemen. At this same time there was a relocation of power because of property exchanges between the count and bishop of Anjou. As a result, much of the significant property of Angers was on the southwest corner on the Maine, so the castle was conveniently moved here.
In the 10th and 11th centuries, Angers was under rule by a line of magnates with the name of "Fulk."" The first count to make this southwest corner his location was Fulk the Red also known as Fulk, or Geoffrey. Among the most famous of the Fulks was Fulk Nerra the Black, who lived from 987-1040 A.D. Fulk Nerra was a great warrior and during much of his reign was in battle with the house of Blois. As a result of his abilities in battle the property of Anjou was greatly increased. After Fulk Nerra came Fulk the 4th, nicknamed "Rechin-, who lived from 1043 to 1109. He was also known as "the rude- and "the quarrelsome- due to his demeanor. Fulk Rechin had little or no effect on the castle, although he remained at the same location as his ancestors.