Constantine's Spolia: A Set of Columns for San Giovanni in Laterano and the Arch of Constantine in Rome

The reconstruction of the Constantinian Basilica at the Lateran by Krautheimer and others leaves several important questions unresolved. A combination of evidence corroborates the reconstruction by Krautheimer of the two rows of nave columns of red granite. Two yellow marble columns which since the end of the sixteenth century support the organ tribune however are never mentioned in relation to the reconstruction of the fourth-century church-basilica. In fact they can be traced back to their medieval presence in the portico on the east side of the building. Their similarities with the equally yellow marble columns on the Arch of Constantine support the notion that they belong to the original, early fourth-century structure of the Basilica Constantiniana. The obvious question where they may have been positioned in the Early Christian basilica can be answered by using the archaeological evidence under the basilica. Part of a foundation running west-east underneath the south transept offers a very likely foundation for a colonnade of two yellow columns on both the north and the south side as a continuation of the rows of green marble columns between the inner and the outer aisles.