This treatment of the monastic complex (also known as Centula) founded by Angilbert ca.790 includes chapters on Angilbert, Angilbert's symbolic understanding, theological issues of the 790s, and a proglomena. A fifth chapter addresses the program of Saint-Riquier: the physical arrangement of the monastery that featured three churches, the largest a basilica dedicated to S. Richarius, and the Holy Savior (known for its early westwork). The number three and trinitarian symbolism was ubiquitous throughout the complex, including the building proportions. The work summarizes what is known of the interior arrangement of the basilica and the other churches, their decoration, and liturgical processions and activities.