Final answer:
The architectural style of the nave of the cathedral is Romanesque, characterized by a fusion of past designs and Roman architectural elements.
Step-by-step explanation:
The architectural style of the nave of the cathedral in Santiago de Compostela, Spain, is Romanesque.
Romanesque architecture was characterized by a fusion of past designs and the incorporation of Roman architecture elements. The nave of the cathedral features vaults, arches, engaged colonnettes, and pilasters that are firmly knotted together, creating a coherent order reminiscent of Roman architecture.
For example, the nave elevation of Ely Cathedral in England, which is a representative example of Romanesque architecture, has three stories - a nave arcade on the ground floor, a gallery with double-light openings above, and a clerestory with triplet openings on the top level.