Tell someone your address is on Park Avenue in New York City, and immediately you've conjured images of luxury, affluence, and status. Over the last two centuries, Park Avenue has become synonymous with the good life - the home of millionaire industrialists since the turn of the last century, it is now the address of wealthy financiers, attorneys, medical professionals, and old-money families who've been there for generations, living in some of the most luxurious co-op buildings in the city.

Like a lot of neighborhoods in the city, Park Avenue wasn't always a bastion of jet-setting socialites and ladies who lunch. In the first half of the 19th century, the street was called 4th Avenue, and the surrounding area was largely comprised of undeveloped farmland. All the urban action was downtown, and what is now Carnegie Hill and Park Avenue was then too remote to inspire much interest.

That all changed in 1831 when railroad magnate Cornelius Vanderbilt connected Lower Manhattan to Harlem via the New York and Harlem rail lines. The horse-drawn railroad was a boon to the area - for a time. When locomotives replaced horses in the 1830s however, the smoke, soot, and constant noise from the tracks turned the idyllic farmland into a dingy rail yard whose only inhabitants were poor immigrants and squatters who built clapboard shacks along the train routes. Between the cinders, the grime, and the fumes coming from Peter Cooper's glue factory below 34th Street, Park Avenue was hardly glamorous or fashionable. It took a massive engineering feat to even make the tulip-colored medians that characterize the street today a possibility.

That feat was the burying of the railroad tracks that ran from the South Street Seaport to Harlem. Once the tracks were covered, the noise and pollution were reduced, and what people know today as Park Avenue began to emerge. The shantytowns slowly gave way to well-built, permanent row houses, occupied by middle-class merchants and businesspeople and their families. As the city expanded uptown, wealthy industrialists began building grand homes along Fifth and Madison Avenues, and the cachet imparted by the nearby Astors, Vanderbilts, and Carnegies eventually trickled onto 4th Avenue, which by then was called Park, and sported a grassy promenade where greasy train tracks once lay.

"It became a status address when the railroad went under the street and they started building luxury buildings there," says Patricia Warburg Cliff, senior vice president of The Corcoran Group, a Manhattan-based real estate firm. "Before that, it was mostly factories and tenements. The earliest really fancy buildings along Park Avenue - the ones with doormen and elevators - date to 1909, 1910; around that time the street began to be seen as a prestigious address."

The expansion of the transportation network of rail and subway led to rapid changes in the way the city's major thoroughfares developed. In the early 20th century, the tunnel that ran into and out of Grand Central Terminal on Park Avenue was built, making the area eminently accessible and creating vast development opportunities for both residential and commercial concerns.

"The fact is that people gravitated more toward large buildings on Park - there never really were townhouses there. When apartment living came into vogue after the Dakota was built [on the Upper West Side], Park became the obvious place to build apartment buildings, because [developers] didn't have to rip up old mansions like they did on Fifth Avenue to gain the real estate on which to build."

And build they did, but on a more restrained, human scale than some of their colleagues downtown. According to Tristan H. Harper, senior vice president at Douglas Elliman's Madison Avenue office, "A beauty of the avenue is that most buildings are of the same height, so when you stand on 57th Street and look up toward 90th, you don't see buildings that are much higher than all the others. Most are around 15 stories. It puts [the neighborhood] on more of a human scale. There are a few towers on Park, but they're rare and considered unwelcome, for the most part."

The development of scores of luxury mid-rise (and a few high-rise) apartment buildings on Park Avenue led to an avalanche of goods and services providers, who moved into the area to serve the moneyed residents of the new "Gold Coast." Most of the new retailers clustered on Madison and Lexington Avenues, establishing the area as the nexus for shopping and strolling that it is today. While many high-fashion retailers and gallery owners have opened large spaces downtown in SoHo and TriBeCa, Fifth and Madison Avenues continue to draw shoppers, as well as families who want the convenience of living near high-end services and top-shelf schools.

According to Janice Silver, executive vice president and sales manager for the Midtown office of Bellmarc Realty, "It's near to everything you want - on Park Avenue, there are a lot of full-service, prestigious buildings - a lot of pre-war apartments with big rooms, deluxe services; big co-ops, mostly, and not too many condos. There are still some rentals, but not a lot of single-family townhouses. That's not really Park Avenue. That's more the side streets off Park."

Of course, Park Avenue stretches from Union Square up into East Harlem, so not every block is the same. The mood and demographic changes from neighborhood to neighborhood as the avenue makes its way up the island.

According to Silver, "The Upper East Side segment of Park is the most affluent, with more choices of buildings. The only other section of Park Avenue that's strictly residential is Murray Hill, in the thirties, but that's a different kind of area. It's not as family-oriented - it's mostly young single professionals without children in the thirties and the fifties. The Upper East Side tends to be much more about families with children."

"You see a lot of baby-strollers on Park Avenue now," agrees Harper. "Especially in the Carnegie Hill section above 86th Street and into the nineties, where all the best schools are. There are traffic-jams of strollers."

According to Cliff, Park Avenue is home to many family-oriented apartments. "There are a lot of young professionals with little kids moving onto Park Avenue and staying," she says, "And more mature families in the seventies to nineties, with the eighties being the most popular blocks because of the schools concentrated in that area."

Of course, convenience, stability, and luxury services don't come cheap. Park Avenue and the Upper East Side are home to some of New York's most prestigious blue-chip properties, and their price tags reflect that. Most residential buildings are co-ops that converted from rentals by the middle of the last century. According to Cliff, "A lot of the co-ops were rentals until the [19]40s, the "˜50s - and then converted to co-ops. Very few of them started life as co-ops."

Regardless of how they started, Harper says that the spaces available on Park Avenue are something truly special. "Most of the pre-war buildings were built when Manhattan was at its peak in the "˜20s and "˜30s, and the proportions of rooms and apartments are gorgeous: they're big and spacious, with six, or sometimes even twelve rooms. Floor-throughs, duplexes, 40-by-20-foot living rooms; they really epitomized the grandeur of New York. A lot of these properties were cut up into smaller apartments [during the Depression], but in the late 1990s, we saw a trend of re-combining them and restoring their original grandeur."

And now, those restored co-ops command some of the most daunting numbers in the city in terms of value and appreciation.

According to Silver, a Park Avenue studio apartment could sell for anywherefrom $300,000 to $600,000, and one-bedrooms range from $500,000 to $850,000. Two-bedrooms can go from around $900,000 to $2 million, depending on whether it's a simple layout or a coveted "classic six." Says Silver, "In a two-bedroom apartment, you'd have two bedrooms, a living room, and a kitchen, and that's it, but in a classic six, you have the same two bedrooms, but it could have a bigger living room, a formal dining room, a maid's room, and a big, eat-in kitchen. Then we're talking about a different kind of property. Anything's possible in those classic sixes."

Cliff agrees, adding that Park Avenue is not the land of modest - or even deluxe - studio apartments. "There aren't many studios. There are a few post-war buildings with smaller spaces, but 85 or 90 percent of the buildings start with six-room apartments."

And according to Cliff, owning property on Park Avenue - regardless of size - is money in the bank. "The prices of these apartments have gone up several thousand percent since 1973," she says. "For example, at 1185 Park Avenue in 1974, a six-room apartment of about 2,000 square feet sold for about $37,500. That same apartment today would go for around $2 million. Luxury apartments may not be moving quite as fast as they were, but anything that's gone up in value that fast has absolutely, in my opinion, held its value. Anybody who has bought New York City real estate in prime locations in the last 25 years has made money, if they kept it for at least two or three years. It's not a risky venture."

As the stock market and economy at large continue to fluctuate, many people are choosing to sink their money into the relatively safe investment that is New York real estate. Park Avenue represents not only stability and wealth, but it also offers safety of another kind; young families are moving back to the area after time away, opting to raise their families in one of New York's safer, more secure neighborhoods.

According to Harper, "In the latest real estate boom, a lot of families came back to Park Avenue. There's a surprisingly high percentage of younger people, which wasn't the case before. Before, Park Avenue was more about well-established people whose families had owned their properties for years, [but now], young people who'd moved out of the city have been coming back after their parents retire, and taking up residence on Park."

Whether you're drawn to the tulips and trees livening up the median, the white-glove service available in the grand old buildings, or the internationally recognized nobility that comes with a Park Avenue, New York City address, the street that once housed horse carts and railroad tracks exudes a powerful appeal. "It's an important place to live," says Cliff, and Harper agrees, "The street is beautiful, convenient, and grand - what else could one want?"