Domes on Axis in the Benedectine Churches of the Terra di BariI (Eleventh-Twelfth Centuries)

The domes-on-axis roofing system having developed in the Terra di Bari during the eleventh and twelfth centuries represents a distinctive architectural scheme shaped by cultural exchanges with the East and facilitated by Benedictine networks. This system features a sequence of domes on pendentives aligned along the nave axis and paired with semi-barrel vaults that evenly balance structural loads. The builders’ understanding of masonry and structural behaviour is evident in their optimisation of load distribution and strategic placement of small windows. Local expertise in ashlar masonry and vault construction was essential to this development. This roofing system was applied above all to Benedictine monastic churches, including the church of Ognissanti in Cuti (Valenzano), San Benedetto in Conversano, and San Francesco in Trani. Among these, the Ognissanti, founded between 1082 and 1083 by Eustasius (†1123?) and likely completed in the early twelfth century, stands as the most refined representative of this vaulting scheme. The former cathedral of Molfetta, the only known example not belonging to a Benedictine monastery, nonetheless confirms the strong typological coherence of this roofing system, whose rigid constructional logic allowed little variation in roofing forms. Although the domes evolved from semicircular to parabolic shapes, this transformation did not significantly alter their spatial or visual impact.