A reflection on the possible acquaintance of two texts, the treatises De Institutio Arithmetica and De Musica compiled by Boethius, that might have been tools of ideation used by the architect in the process of project for Sant Fructuós de Tàrraco’s northern basilica is presented. A system of dimensions in accordance with arithmetic elaborations compiled by Boethius is proposed for the graphic survey of the basilica’s excavation. A new reading of the archaeological floor rehearses a dimensional scheme for other architectures that sprung from texts such as the De Institutio Arithmetica and De Musica and its subsequent applications. The arithmetic and music compiled by Boethius was one of the rules used to shape Sant Fructuós at Tarraco’s northern basilica. As noted by González Pérez (2016), some dimensionsadsdas of the floor of the basilica and the atrium of Sant Fructuós generate chords, though in different octaves