The remainder of the interior is now singularly undecorated and severe. The entrance has been so much transformed by later additions that, in place of the original portal and vestibule, there remains only a vestibule considerably narrower than the nave, compressed on one side by the huge towers of the new Cathedral, and on the other by later alterations. The two older towers which contained, one the chimes and the other the dwelling of the Alcaide, have quite disappeared. The vestibule has excellent allegorical sculptures and Gothic statuary.
The northern aisle still has a few mural paintings, but the larger part of those which once illuminated the bare walls were washed off by a bigoted prelate in the fifteenth century and the present gray of the stone, as seen in the dim light, looks cold compared to the rich gold of the exterior masonry bathed in sunshine. The excellence of the vaulting is such that to-day hardly a fissure or crack is visible. The old pavement consists of great rectangles marked by red sandstone borders and bluestone centre slabs, the size of a grave, with central dowels for lifting and closing. In the southern transept-arm leading to the cloisters, some of the original windows are still preserved with their fine columns, archivolts, and carved moldings. The ribs of the vaults are decorated by zigzag ornamentation, and here a few magnificent old tombs remain intact in their ancient niches.
There is, properly speaking, no exterior elevation of the whole structure. The western front is hidden by the modernization, the north and south, by the new Cathedral, the cloisters, and squalid, encumbering walls and chapels. From the "Patio Chico" alone, the old structure can be seen unobstructed. The curves of the apses bulge out like full-bellied sails, their great masonry surfaces broken by the small windows, which are cut with enormous splays and encased and arched by typical Romanesque features, the windows protected by heavy Moorish grilles. Engaged shafts run up the sides of the central apse to below a quatrefoil gallery, originally a shelter for the archers stationed to defend the building. Two fortress-towers formed the eastern angles north and south; the one to the north was removed in building the new Cathedral. A scaled turret, broken by later Gothic pediments, crosses the one remaining. Above all soars the dome, the inspiration of our greatest American Romanesque temple, Trinity Church in Boston.