Such a view of the heart of the Exposition at its best compels
recognition of Guerin's skill in color. It needed a vivid imagination to
realize the possibilities of the scene, and visualize it. It required
infinite delicacy and a fine sense of the absolute rightness of shade
and tint to produce such harmonious beauty. The mere thought of it is a
lesson in art.

The decision of the architects to develop the theme of an Oriental
walled city, and the natural setting of the site, Mediterranean in its
sea and sky, led Guerin to select Oriental colors. Aiming at simplicity,
he decreed that not more than eight or nine colors should be found upon
the subdued palette from which he would paint the Exposition. Then he
took into consideration the climate and atmospheric conditions peculiar
to San Francisco. Every phase of sky and sea and land, every shadow upon
the Marin hills, across the bay, was noted in choosing an imitation of
natural travertine for the key color of the Palaces.

This is a pale pinkish-gray-buff, which may be called old ivory. It is
not garish, as a dead white would be, especially in the strong
California sunlight, but soft and restful to the eye. It harmonizes with
the other colors selected, and, most important of all, it avoids a
certain "new" effect which pure white would give, and which is deadly to
art.

Paul Deniville, who had already developed a successful imitation of
travertine, was engaged to make the composition to be applied over the
exterior walls. This is a reproduction in stucco of the travertine
marble of the Roman palaces of the period of Augustus. This marble is a
calcareous formation deposited from the waters of hot springs, usually