PHILADELPHIA -- The approach to the new Barnes Foundation campus in Center City Philadelphia is not a straight line. Visitors to Dr. Albert C. Barnes’ extraordinary art collection first walk by a ticketing pavilion, then past a newly commissioned zigzag sculpture by Ellsworth Kelly. Beyond that is the main building, a subdued rectangle of pale gray limestone bordered by a reflecting pool and a row of red Japanese maple trees. Near the entrance, the path turns left, across paving that bridges the water, suggestive of a protective moat. Then visitors must turn right to enter the building through a pair of heavy, wooden doors.

This journey is neither long nor arduous, but it is symbolic. In 1922, when Dr. Albert C. Barnes established his foundation, he said its mission was “the advancement of education and the appreciation of the fine arts.” He bought a 12-acre arboretum in Merion, a Philadelphia suburb, and commissioned a residence for himself and his wife, Laura, and a building for his artwork.

It opened to the public in 1925 in a limited way. Admission had to be requested in advance, and Barnes was selective. He refused entry to celebrities, art critics and socialites — the likes of whom had offended or snubbed the boy from the slums of Philadelphia who studied medicine at the University of Pennsylvania and went on to invent Argyrol, an antiseptic that made him a fortune.

Court records show that in 1956, only 326 people were allowed to view Barnes’ Renoirs and Cézannes, his paintings by van Gogh and Matisse, Picasso and Seurat, his El Grecos, his Rousseaus, his canvases by Soutine and Modigliani, Goya and Frans Hals, his African art collection, his Native American jewelry, his textiles and ceramics and metalwork and more.

In 1961, by court order, the galleries were opened to the public on Fridays and Saturdays without reservations. However, even then attendance was limited. The trip from Center City to Merion was time-consuming and entailed a train or a bus ride plus a half-mile walk, or access to a car.

The entrance to the new Barnes reflects that convoluted expedition. Moreover, it imposes a break from the city and a transition from its bustle to a place of serenity and quiet.

In yet another way, it recalls a transition that was lengthy and anything but straightforward. When he set up the foundation, Barnes stipulated that all his paintings were to remain exactly as they were at the time of his death and that of his wife. Nothing was to be moved or loaned.

Barnes was killed in an automobile accident on July 24, 1951. Laura died in April 1966.

By 2002, the Barnes Foundation was in financial distress, with a depleted endowment and inadequate operating revenue. The trustees petitioned the court Orphans’ Court of Montgomery County to move the collection from Merion to Center City Philadelphia in order to attract a wider audience. After much legal wrangling, the request was approved. With new management at the helm, in 2007 the Barnes Foundation hired Tod Williams and Billie Tsien to design a building for its four-and-a-half acre campus on Benjamin Franklin Parkway next to the Rodin Museum and down the hill from the Philadelphia Museum of Art.

On May 19, the new Barnes opened to the public. .

Within a 93,000-square-foot building that includes an auditorium, library, seminar rooms and dining facilities, the architects have re-created the 12,000-square-foot Merion galleries down to the last details of crown moldings, window size and placements and scale. Their changes have been subtle: lightening the finishes on the wood, utilizing simple floor patterns and reshaping the ceilings to enhance the lighting.