Oakham, Decorated Spire of, [60].

Ogee-shaped arch, [129].

Oppenheim, St. Catherine at, [107].

Orleans, Capital from house at, [197].

Orleans, Window at, [196].

Pavia, Certosa, near, [114], [188].

Palladio, Architect, [172], [184], [187].

Paris, Cathedral of Notre Dame, [74].

—— Hôtel des Invalides at, [205].

—— Louvre, Capital from, [202].