The Cosmatesque floor is from the 15th century, a late example of this technique. It was paid by the Colonna family, and completed in its present form in 1425 under Pope Martin V Colonna, who ordered marbles be taken from ancient monuments from around the city to complete the work. The Colonna family's coat-of-arms, a column, can be seen in several places on the floor. The floor was renovated in 1934-1938, during wich a reinforced concrete subfloor was added to support the ancient floor.