The moment that has been chosen to celebrate the 150th anniversary is July 21 -- the date in 1853 when the New York State legislature passed legislation taking the land that is now Central Park off the private real estate rolls and legislating that it become public property.

Manhattan real estate is rather precious, so this was a momentous decision that took a great deal of political will. It required a general consensus among the population and the politicians that there had to be a park.

The need for a great central park in New York City goes back to the beginning of the 19th century and the creation of the grid plan in Manhattan. In 1807, the city was on the cusp of growth. Astute city builders knew that Manhattan's location, the quality of it port, the proximity of the Hudson River, and the idea that there would be an Erie Canal, would make this the city of commerce in America and that growth would be extraordinarily rapid.

The challenge was how to plan for it, and the planners came up with a very practical and logical scheme: 12 broad, north-south avenues and 155 narrow, east-west streets from Houston to 155th Street. This plan was imposed upon a very irregular, rocky, somewhat hilly landscape but had nothing to do with any of the natural topographical features. The only open of any size was between 23rd and 34th streets. Called "The Parade," it was a place for the local militias to exercise. By 1830 this park was gone, and because of great pressures of real estate development, all public land had disappeared.

Even the most stalwart builder knew that the city was going to require some sort of a park for peace and safety. People were beginning to think there had to be some reaction to the total control of Manhattan by the grid-planning of 1811. Andrew Jackson Downing, the editor of a very important magazine called The Horticulturalist, who had the ear of lots of Americans, started editorializing that New York needed a park of at least 500 acres. William Cullen Bryant, a leading poet and journalist, also editorialized about the need for major park.

By the 1851 mayoral elections, both the Democrats and the Republicans campaigned for a public park. The question was where, how and what is it going to look like.

Two locations were considered. One was Jones' Wood, a plot of land on the East River that was about 150 acres and pleasantly landscaped. You could easily put up a sign that said "New York Park," let the people in, and you would have been done. But it was not central, it only would have served a certain area, and it was not big enough. People like Andrew Jackson Downing said, "This is inadequate; it will not do."

The other choice was the site that we know today. It was already the site of the first great public works project in New York City, which was the Croton Water System. In the mid-1830s, the city found that if it did not come up with a municipal water supply that was adequate and sanitary, the city could not grow.

So a huge public works project was completed in 1842. Water from the Croton River in Westchester County was brought 42 miles across the East River into the Receiving Reservoir between 6th and 7th avenues, between 79th and 86th streets. From there it went down to 42nd Street and 5th Avenue to the Distributing Reservoir on the site of what is now the New York Public Library. By 1853, the managers of the Croton System began to survey for a huge North Reservoir, which still exists today north of 86th street.

There was a compelling logic that if you were going to take land from the private market for a park it should be tied in with the two reservoirs so the land between them would not be wasted. This was the anchor upon which the park was based. The receiving reservoir, which was filled in in the 1930s, is now the Great Lawn -- the park’s geographical center.

In 1853, everyone had agreed that the land around the reservoirs would be the place for the park. It would be about 848 acres, big enough to suit the requirements of landscape architects.

But it was a very unprepossessing piece of real estate. No one would have chosen it for its beauty or charm. It was rough, rocky and swampy, and it required a vast amount of work to make it into what it is today.

A board of commissioners for the park was established and hired a very accomplished engineer named Egbert Viele. He surveyed the area of the new park and did a pen-and ink drawing in 1855 of a design for a drainage system.

Meanwhile, in 1852, A.J. Downing had died saving victims of a tragic accident that occurred when two steamboats got into a race on the Hudson River. Just the year before he had brought back from England a young man named Calvert Vaux, a trained architect. Vaux looked at Viele’s design, which had been accepted, and said, “This is terrible. This is not adequate. Downing would not approve.” He began politicking behind the scenes and persuaded the commissioners to drop the plan and have an open competition.

The competition was announced in 1857, and 33 proposals were submitted in the spring of 1858. Twelve of the 33 were done by people who were already involved with the creation of the park. Few of these proposals have survived.

The proposals had to honor and incorporate 10 requirements. There had to be a playground, a parade ground, a cricket ground, a flower garden and a group of buildings for exhibitions.

How did Calvert Vaux, having started the competition, get into it himself? He realized he did not have the ability to do the whole thing himself. He did not know the topography well enough. And he also knew that if he were lucky enough to win, he would not have the ability to execute the plan. So he found Frederick Olmsted, who had lost all his money by investing in a publishing business and then ended up as superintendent of Central Park in 1857. Olmsted was working everyday in the park on horseback and knew everything about it.

Vaux persuaded Olmsted to join him in drafting a proposal for this competition. The two of them worked together every evening through the winter of 1857. Their entry was the last submission, and they won.

Vaux and Olmsted included all the things that the competition required: a parade ground, a playground, a flower garden, a conservatory, a museum area, cross streets, a skating park. But all of this was of no real interest to Vaux and Olmsted. What they saw was an opportunity to transform this piece of raw, rocky, narrow, very unsympathetic nature. They were given the worst possible playing deck of cards, the most unpromising piece of land, and that forced them to think outside the box.

The idea was to separate this piece of nature from the city entirely. Once you enter the park, you do not want the city to be included.

Vaux and Olmsted proposed great open areas, which they saw as beautiful landscapes; they saw it as a great, English, stately home meadow. This required major transformations of nature. Ten million cartloads of earth and rock were moved. Far more than simply creating a park, it was transforming nature into a work of art.

Vaux and Olmsted got the commission and went ahead with it. Theirs was a great partnership because they were complimentary in their talents.Vaux did everything architecturally. He designed all the buildings and the 35 or 36 bridges, most of which survive today and are the great glories of Central Park. The original design had only a half dozen bridges. But shortly after the plan was accepted, commissioner August Belmont said there needed to be bridle paths in the park. That requirement meant 35 or 36 bridges.

The biggest architectural component of the park was the Bethesda Terrace, which survives today and was one of the grandest public buildings in New York. It is virtually invisible unless you see it from the right angle; the point that Vaux was making was that architecture should always be subsidiary to nature in Central Park. And that may be why Vaux has, historically, been second fiddle to Olmsted. Vaux was not as charismatic, but he was crucial to the Central Park’s creation.

Central Park cost about $10.5 million. This was big money at the time -- the land alone cost more than $1.5 million. And in October 1857, times were really tough. How did they win approval for this huge public works projects.

The economic panic was a blessing in disguise because the politicians wanted to employ all these people who were out of work. Olmsted had up to 4,000 people on his payroll in 1859-61. It was not until 1862 and the Civil War draft that the numbers went down. Between 1858 and 1861, virtually the entire park up to 79th street, the most complicated part, was built. It was an extraordinarily rapid achievement using the best materials and no shortcuts.

The park was immensely popular from day one, and its constituency was as varied as the city -- and as varied as it is today.

Morrison H. Heckscher is the Lawrence A. Fleischman chairman of the American Wing at the Metropolitan Museum of Art. This is adapted from a lecture he gave in conjunction with the museum’s exhibition, “Central Park: A Sesquicentennial Celebration,” which runs until September 28, 2003.