I played the song repeatedly. Today, I can still hear the scratchy tune. I've never forgotten its title: "Those Wedding Bells Are Breaking Up That Old Gang of Mine." An Internet search tells me that the song was written in 1929 by Irving Kahal, Willie Raskin, and Sammy Fain. Melodic and rhythmic, it was an instant hit, recorded frequently over the years. But at the time, I knew nothing of that. Nor did I understand the emotions of the lyrics, which described the loneliness of a young man whose friends are all getting married. What captivated me was that scratchy sound. It came palpably from the past and served as a time tunnel through which my imagination could travel back to other years. I visualized the vocal group in unfamiliar clothes, surrounded by unfamiliar objects, singing out-of-fashion music in a setting that was always fuzzy and in black-and-white. Regrettably, I don't recall the group's name. So much for immortality.

Since then, I've obeyed a compulsion to investigate many other abandoned buildings, not to mention tunnels and storm drains, although I never again found anything so memorable as that phonograph album. I assumed that my traumatic childhood accounted for my fascination with crumbling deserted structures and that I was alone in my obsession with links to the past. But I now realize that there are many like me.

They call themselves urban explorers, urban adventurers, and urban speleologists. Their nickname is creepers. If you type "urban explorer" into Yahoo, you'll find an astonishing 170,000 Internet contacts. Type that name into Google, and you'll find an even more astonishing 225,000 contacts. It's a reasonable assumption that each of these links isn't represented by just one lonely explorer. After all, nobody's going to put together a site if he/she doesn't have a sense of community. Those hundreds of thousands of contacts are groups, and logic suggests that for every one that publicizes itself, there are many others that prefer to be hidden.

Those who wish to remain anonymous have a good reason. Bear in mind, urban exploration is illegal. It involves the invasion of private property. Plus, it's so unsafe it can be deadly. The authorities tend to insist on jail terms and/or serious fines to discourage it. As a consequence, many of these websites emphasize that explorers should get permission from property owners and that they should always follow safety precautions and never do anything against the law. Those warnings sound socially responsible, but my assumption is that for many urban explorers, part of the appeal is the risk and thrill of doing what's forbidden. It's significant that their slang term for entering a deserted building borrows from the covert-ops military expression for invading hostile territory: infiltration. As the website www.infiltration.org indicates, the objective is "places you're not supposed to go."

Creepers are mostly between the ages of eighteen and thirty, intelligent, well educated with an interest in history and architecture, often employed in professions related to computer technology. They share a worldwide interest, with groups in Japan, Singapore, Germany, Poland, Greece, Italy, France, Spain, Holland, England, Canada, the United States, and several other countries. Australian groups are fascinated with the maze of storm drains under Sydney and Melbourne. European groups favor abandoned military installations from the world wars. U.S. groups are drawn to classic department stores and hotels abandoned when social decay led to an exodus from cities like Buffalo and Detroit. In Russia, creepers are obsessed with Moscow's once-secret multi-level subway system intended for evacuating Cold War officials during a nuclear attack. Deserted hospitals, asylums, theaters, and stadiums: Every country offers plenty of opportunities for urban exploring (see Mark Moran's essay, "Greetings from Abandoned Asbury Park, NJ," at www.weirdnj.com).

One of the first urban explorers was a Frenchman who in 1793 became lost during an expedition into the Paris catacombs. It took eleven years for his body to be discovered. As a character in Creepers indicates, Walt Whitman was another early urban explorer. The author of Leaves of Grass worked as a reporter for the Brooklyn Standard, where he wrote about the Atlantic Avenue tunnel. Touted as the first subway tunnel anywhere when built in 1844, it was discontinued a mere seventeen years later. Before it was sealed, Whitman trekked through it. "Dark as the grave, cold, damp and silent," he wrote. "How beautiful look earth and heaven again, as we emerge from the gloom! It might not be unprofitable, now and then, to send us mortals, the dissatisfied ones at least, and that's a large proportion, into some tunnel of several days' journey. We'd perhaps grumble less, afterward, at God's handiwork."

But Whitman didn't get the point of urban exploration. He saw the tunnel in negative terms. For a true devotee, however, the cold, damp, silent darkness of a tunnel or an abandoned apartment complex or a deserted factory is exactly the goal. The spooky attraction of the eerie past: I suspect that's what a much later explorer felt in 1980 when he uncovered that same Atlantic Avenue tunnel 119 years after it was barricaded and forgotten.

A major modern instance of urban exploration occurred recently in the Paris catacombs. Those catacombs are part of a 170-mile tunnel system beneath Paris, the consequence of quarry work that over many centuries provided building materials for the city. In the 1700s, some of the tunnels were used to store thousands of corpses when Parisian cemeteries exhausted their space. In September of 2004, a French police team on a training exercise found a fully equipped movie theater among the bones. Seats had been carved into the rock. A small adjoining cave functioned as a bar and restaurant, with whiskey bottles on display along with professional electrical and telephone systems. Another major example occurred in Moscow in October of 2002 when Chechen rebels seized control of a theater. After the military surrounded the building, a Russian urban explorer guided soldiers inside through a forgotten tunnel.

Some of this is adventuring in a basic sense. But I think that there are also psychological implications. As I note in Creepers, our world is so fraught with elevated threat levels that it makes a lot of sense to retreat to the past. Old buildings can be a refuge, drawing us back to what we imagine were simple and less stressful times. In my youth, the deserted apartment complex provided an escape from the turmoil of my family. I was a time traveler, finding sanctuary in a past that appealed to my imagination and in which there were never any arguments.

In my youth. As an adult, I now have a different perspective, one with deeper, less comfortable implications. To me, old buildings have become like old photographs. They remind me how swiftly time passes. The past they evoke draws attention to my ultimate future. They are an opportunity for reflection.

I recently had the chance to visit the high school I attended more than forty years ago. A part of it had burned to the ground. Most of the remainder has been boarded shut for a decade. When I entered, a hazard team was checking for asbestos, lead paint, and mold, prior to the school's renovation. It's amazing what years of disuse can do, especially when broken windows allow rain and snow to intrude. In disturbingly silent hallways, the hardwood floors were buckled. Plaster drooped from the ceilings. Paint strips hung from the walls. But in my memory, everything was clean and well maintained. I envisioned students and teachers filling the noisy corridors. The trouble is, many of those students and teachers have long since died. In the midst of decay, my imagination conjured youth and the promise of hope, gone just as the school would soon be gone.