To accomplish this, Alberti relinquished the notion of conventional side aisles and created cross-axial chapels instead. Each chapel is barrel vaulted and seems like the passageway through a triumphal arch. The openings are separated by wall elements opened by small doors. These doors give access to intermediate chapels of smaller size.
In this way, the interior of Sant' Andrea is integrally related to the exterior expression. The effect of the interior is much like the interior of the Roman baths, although that was not Alberti's intention. The important aspect is the similarity of character between the church and its general Roman antecedents with regard to mass, scale, proportion, monumentality, and detailing. The church now seems more Roman and less medieval.