This year, with surprisingly little fanfare, Central Park is celebrating its 150th birthday. Five years ago, there were fireworks and daylong festivities to mark the sesquicentennial of the city’s decision, in 1853, to build a great urban park in the middle of Manhattan. But it was in 1858 that the municipality finally decided upon the so-called Greensward plan of Frederick Law Olmsted and Calvert Vaux, and it was in that year as well that the great work began.

I know serious students of architecture and urbanism who are happy to assert that Central Park is the finest work of art, the finest aesthetic object, the finest thing in New York City. No other city, not even those that can boast parks created by the same pair, has achieved a comparable perfection. Simply put, you can say of Central Park what Wordsworth, in “Tintern Abbey,” says of nature itself: “For nature then … To me was all in all.” Uniquely among urban parks, Central Park is able to envelop the mind and the senses of those who enter it in a receptive mood, in such a way as to inspire that tingling sense, usually associated with mountains or oceans, of something immense and inexhaustible. And that inexhaustibility, by the way, is a benchmark of all great art, whether in a symphony, a cathedral, a novel, or a film, the sense that you can never grasp all of it together or reach the limits of what it has to offer.

By itself, the establishment of that goal of inexhaustibility, never mind its attainment, was a milestone in the development of cities. Think of the other great parks of the world: the Luxembourg Gardens in Paris and the Villa Borghese gardens in Rome, Hyde Park in London and the Emerald Necklace in Boston, Golden Gate Park in San Francisco and Brooklyn’s Prospect Park, which was also designed by Olmsted and Vaux. Few of them aspire to, and surely none of them attains, that all-important quality of totalizing envelopment that is so conspicuous in Central Park — and this notwithstanding the nearly omnipresent skyline and the sounds of traffic that filter into the park from beyond its confines. Whether in the formal gardens of the Tuilleries and the Luxembourg or in the more naturalistic landscaping of Hyde Park and Regent’s Park, the urbanite has at each moment the sense that he is standing in an all too finite oasis in an expanding city.

Through their layout and siting in the urban fabric, the Villa Borghese gardens and Golden Gate Park succeed better in establishing a provisional autonomy from the cities that surround them. But they, like Prospect Park, lack the ingenious variety that is the secret of Central Park’s success. Only conceive of Central Park without its trees and landscaping: Instantly it would stand exposed as something rather small. Half a mile wide and 2 1/2 miles long, it is scarcely bigger than Hyde Park together with the contiguous Kensington Gardens. From any point in those two parks, you can see every other point, not to mention the city beyond.

In Central Park, by contrast, an astonishingly successful illusion of size is conjured up through the constant and artful obstruction of sight lines. It is hard to see more than 200 feet in any direction: Your gaze is interrupted by a rock arising out of nowhere, by the sudden appearance of trees, or by some piece of architecture, such as the Arsenal, the Bandshell, Bethesda Terrace, or Belvedere Castle. And yet these successive events and detours never seem forced or constraining. Though almost everything you see in Central Park, even the lake in the very center, is man-made, still the overall effect seems as natural as nature itself. And then there are the suddenly expanding vistas of the Sheep Meadow, the Great Lawn, the Reservoir, and the North Meadow, which occur at just the right moment to dispel — if there were any risk of it — a sense of confinement.

As crucial to the achievement of Central Park’s overall effect is a constant variation in the style and feel of what presents itself to the eye. Water alternates with fields, and the Beaux Arts parade ground of the Mall and Bethesda Terrace, the most artificial and “French” stretch of the park, alternates with the untouched rusticity of the Ramble. It is a testament to Olmsted and Vaux’s sovereign mastery of their profession that most people are never even consciously aware of the perfect balance that was attained: Rather, it infuses them at a subliminal level. How easy it would have been for one element, the rustic or the man-made, the thickets or the clearings, to predominate and thus to reduce the rest of the park to the status of an afterthought. But in Olmsted and Vaux’s masterpiece, that is never permitted to occur.

Finally, we should not allow ourselves to forget that, in a city with few buildings more than 125 years old, the biggest single thing in Manhattan is a thoroughly Victorian, antebellum park, whose specific details and overall effect have changed very little over the years, despite a thousand tactical revisions. And yet, Central Park never feels landmarked or antique. At 150 years old, it is reborn with each changing season.