Frederick Law Olmsted once said, of the area that would become Central Park, that it would have been hard for New York City’s leaders to choose a piece of land that possessed fewer of the “desirable characteristics of a park, or upon which more time, labor, and expense would be required to establish them.” In their submission to the design competition for Central Park, Olmsted and Calvert Vaux include “before” images showing an unprepossessing landscape: barren fields, marked only by scrub growth and the occasional boulder.

As New Yorkers know, Olmsted and Vaux’s design — called the Greensward plan, which the commissioners of Central Park selected in a vote on April 28, 1858 — would ultimately transform this unpromising 600-acre parcel into one of the most beautiful urban parks in the world. This spring, the New York City Department of Parks & Recreation, the Central Park Conservancy, and two New York museums have planned a series of events to mark the sesquicentennial of the adoption of the design.

On April 23, the physical Greensward Plan, which is 10 feet long and usually hangs on a wall in the Parks Department offices, will go on exhibit at the Arsenal Gallery, along with historical photographs that capture Gilded Age New Yorkers strolling on the Mall or riding the swan boats on the Pond. One photograph, from the 1869 annual report of the commissioners, shows a camel from the Central Park menagerie hitched to a mower on Sheep Meadow.

On Saturday, April 26, as a kickoff to the actual anniversary weekend, the Metropolitan Museum of Art will host a conversation among a group of historians and the Met’s Lawrence A. Fleischman Chairman of the American Wing, Morrison Heckscher. On Sunday, senior staff members of the Central Park Conservancy, including its historian, Sara Cedar Miller, will lead free tours and discuss aspects of the park’s behind-the-scenes operations.

In addition, this Wednesday, Mr. Heckscher will speak at the National Academy of Design on the architect Richard Morris Hunt and Central Park — a relationship that is the subject of the National Academy’s current exhibition. In honor of the anniversary, the Met has published a book by Mr. Heckscher, “Creating Central Park.”

The discussion on April 26 will likely focus on the respective contributions of Olmsted and Vaux to the design. As Mr. Heckscher notes in his book, Olmsted has typically received more of the credit, even though “[t]hey agreed early on and stuck to it that they deserved equal credit for the design,” the series editor of the Frederick Law Olmsted Papers Project, Charles Beveridge, said. The only areas in which they did not divide credit equally were the design of the architecture and bridges, for which Vaux took credit, and the administration and management of the construction process, a responsibility that Olmsted primarily shouldered.

From the beginning, though, Vaux worried about his contribution being forgotten, and history in large part proved his fears justified. Not only did Olmsted’s personality, administrative position, and writing career make him better suited to be the public representative of the park, but after 1872, when Vaux returned to architecture, Olmsted continued to work in landscape design. He established the leading firm in the country, which was then carried on by his sons.

As a result, Mr. Heckscher said in an interview, “The name Olmsted was inextricably tied with parks.” When they began their partnership, Vaux had the superior training. After studying architecture in England, he was recruited to New York in 1850 by Andrew Jackson Downing, a garden designer and the editor of the Horticulturalist. Downing and Vaux worked together until 1852, when Downing died in a steamboat accident on the Hudson River.

Downing had been an early advocate of the creation of a Central Park in New York and almost certainly would have been its designer if he hadn’t died. Instead, Egbert Viele, who had been appointed the chief engineer for the park, tried to make the acceptance of his own design a fait accompli. When the park’s commissioners published their first annual report in 1857, they included his plan.

It was Vaux, Mr. Heckscher said, who saw the shortcomings in Viele’s plan, in which relatively uniform parcels of land were divided by wiggly drives. Vaux persuaded the park commissioners to hold a competition for the design and then convinced Olmsted, who had been named superintendent of the park, to collaborate with him on a submission.

The two men worked on their plan in the evenings, at Vaux’s home on East 18th Street. They submitted it on March 31, 1858, just before the April 1 deadline; theirs was the last entry submitted.

The major practical genius in Olmsted and Vaux’s plan was their decision to submerge the four required transverse roads, which connected the east and west sides of the city. That meant that traffic could move efficiently across the park, without disturbing the park visitor’s sense of being outside the city.

Their design of the park’s beautiful sequence of vistas was also crucial. Philosophically, they envisioned the park landscape as a work of art, a professor emeritus at Buffalo State College and Vaux’s biographer, Francis Kowsky, said. “Some of the passages — the way they arranged the landscape with water or hills — are very close to Hudson River School paintings,” Mr. Kowsky said, noting that Vaux was friends with several painters, including Frederic Church, and Vaux’s brother-in-law, Jervis McEntee, who painted some of the watercolors that Olmsted and Vaux included with their competition entry to show how the park would look.

In the 19th century, “there was a great deal of intimacy between the art of landscape architecture and the art of painting, which we tend to lose today when parks are more recreation areas,” Mr. Kowsky said. Olmsted and Vaux believed that a park should provide relief from the city’s artificial environment and thus restore a certain psychological balance.

After Central Park, Olmsted and Vaux went on to design Prospect Park, as well as parks in Buffalo, and the Niagara Reservation at Niagara Falls. They remained friends for the rest of their lives, even as Olmsted’s star rose and Vaux’s fell. In 1872, when they stopped collaborating, Vaux had in hand three architectural commissions: for the two museums on the park, the Metropolitan and the American Museum of Natural History, as well as for a huge vaulted pavilion for the 1876 Centennial Exposition in Philadelphia.

“These would had been the three largest buildings in North America if they had been completed,” Mr. Kowsky said. But over the course of the decade, each of the commissions fell apart. The Museum of Natural History and the Exposition pavilion were eventually turned over to other architects. Only a small part of Vaux’s design for the Metropolitan was completed — the area that is now the Medieval Sculpture Hall. In 1895, the design for the Met’s façade was eventually given to Richard Morris Hunt, whose ambition to design grand, French-influenced gates along the south end of Central Park had been thwarted by Vaux’s opposition. (The exhibition at the National Academy includes Morris’s drawings for the gates.) The anniversary is also a time to reflect on the travails that the park has endured through the last 150 years, and how close at times its beauty has come to being permanently destroyed. By the 1970s, the park was no longer a respite from the urban environment, but a blight on it. There were no trained gardeners working there, the parks commissioner, Adrian Benepe, recalled in an interview.

“Abandoned burned-out buildings would sit for years,” he said. “Belvedere Castle was abandoned. Sheep Meadow and the Great Lawn were literally dust bowls.” Statues were missing arms and legs. Bethesda Fountain and Bethesda Terrace were covered with graffiti, as were the rowboats. “There was even a giant piece of graffiti on one of rocks,” Mr. Benepe said. In the psyche of the city, Central Park was not a place you went to find balance; it was a place you got mugged.

It was through the activism of Elizabeth Barlow Rogers, who in 1977 published a book on how to rebuild the park, and the hard work of the Central Park Conservancy, which was founded in 1980, that Olmsted and Vaux’s work of art was eventually restored, Mr. Benepe said.

Today the Conservancy has almost finished a fund-raising campaign that it hopes will protect the park from the vicissitudes of government funding. It has so far raised $114 million. The Conservancy’s president, Douglas Blonsky, said he wants to reach $120 million.

“Our goal is to secure the future,” Mr. Blonsky said. “We want to break that cycle of [periodic] decline.”