New Yorkers who enjoy a leafy journey north to the Hudson Valley and the Berkshires have a welcome addition to their array of attractions: the new extension of the Sterling and Francine Clark Art Institute in Williamstown.

The Stone Hill Center is set a little distance from the core of the collection, up the hill from the art museum and nestling in trees. It is the new building’s location almost as much as its unusual design, by the Japanese autodidact architect Tadao Ando, that sparks the imagination.

One of the tantalizing aspects of the Berkshires is that there are few adequate ways to look out upon the undulating woodlands and contemplate the beauty of the landscape. But the new addition to the Clark has opened up two new vistas. Visitors to Williamstown can now grasp a better perspective not only of the museum’s array of largely American art but also of the teeming spires and columns of the university town nestled in the forest landscape. The new building urges visitors to abandon the indoors and head west across country, up the gentle slope of a wide meadow saturated with grasses, flowers, shrubs, and the opportunely placed tree or two.

Once there, the full sweep of the Williamstown valley appearsin a fresh and dazzling light. In all directions, the blue woodlands form a dramatic, almost operatic backdrop against which the handsome towers and ornate buildings sit in their sedate glory.

There are few art collections in the world that prompt you first to take an amble through the surrounding countryside, and those who accept the Clark’s rustic invitation are amply rewarded. Relaxed and refreshed, the mind cleared of the debris of mundane thoughts, the brain oxygenated by fresh air, visitors are suitably prepared to explore the Clark’s pictorial delights with a fresh clarity.

For those who wish to admire Mr. Ando’s building, home to the Williamstown Art Conservation Center, there is an alternative ramble along a newly created path that wanders through the wood to the south of the main building. Again, the effect of taking this short sylvan meander, gently uphill but accessible for everyone whether nimble or encumbered, is to purge the imagination of humdrum concerns so that, by the time the visitor emerges at the approach to the quiet masterpiece of a building, the critical faculties are fully prepared for inquiry.

The center’s understated doorway borrows from Japanese architecture, building upon the tranquillity acquired in the glade to suggest the entrance of a temple or the dwelling of an aesthete. Once inside, the first sensation is not of an enclosed space but an appeal to walk outside again — through the facing glass doors to the valley side of the building — and enjoy the vista. The terrace café, with its novel views over Williamstown and the hills beyond, is an essential coffee or lunch stop on any visit to the Clark.

Currently on show is “Homer and Sargent from the Clark,” featuring 12 mostly familiar canvases by Winslow Homer and John Singer Sargent. The pictures, chosen as much to show off the wonders of the new gallery space as to make an explicit point, complement a larger exhibit in the main gallery down the hill.

Also in the Center are the ample private quarters of the conservators for whom the building has been principally designed. An opportunity to eavesdrop on their labors is provided by a staircase at the front of the terrace that descends into a triangular atrium enclosed by a glass screen on one side. The conservators can be seen plying their specialist skills.

What can also be seen is the vast concrete wall that slices through the rectangular building like a giant descending guillotine. It is the most puzzling aspect of Ando’s design, concealing the activities of the conservators from without while guarding the building and its occupants from the forest as if it were a protective and forbidding castle wall.

The Homer and Sargent pictures in the new galleries are a foil for “Like Breath on Glass,” a seductive array of gentle, subtle images mostly by James McNeill Whistler and George Inness, as well as William Merritt Chase, John Twachtman, Edward Steichen, and others, in an exhibit the curator Marc Simpson aptly dubs “painting softly.”

Small enough to absorb in one sitting, and best enjoyed at a leisurely pace, this perfectly hung selection submerges the viewer in the sumptuous, mystical, and magical world observed and recorded by these minor masters 100 years ago. There are surprises and discoveries here even for those who think they know Whistler, as well as the pleasure of discovery of artists who have long lived on the edge of greatness.

“Homer and Sargent from the Clark” until October 26; “Like Breath on Glass: Whistler, Inness, and the Art of Painting Softly” until October 19. For more information,visit clarkart.edu.