We climbed 16 flights of slippery, icy stairs in an abandoned apartment building — the iron railings long ago pilfered, balcony doors stuck open — until we reached the roof and peered over the ghost town of Pripyat, the once-hailed Soviet “futuristic city” where Chernobyl nuclear plant workers and their families lived.

Thirty-three years after the Chernobyl nuclear reactor explosion, Pripyat’s broad boulevards are crowded with tangles of overgrown trees. Its once gleaming buildings are dark and brooding — windows gone, interiors looted, hallways littered with crumbling books.

It was twilight, and from our rooftop perch, the only light we could see came from the silver dome encasing the Chernobyl reactor, lit up as if it were still on fire. Someone in our group blasted music from an iPhone, and suddenly a dozen Americans broke out dancing. We were among the only humans in this deserted city.

“What else do you do at the end of the world?” someone yelled.

Welcome to the apocalypse vacation: a weekend in Chernobyl.

Ever since the Ukrainian government opened Chernobyl to tourists in 2011, the number of annual visitors continues to climb. Last year, the government reported nearly 72,000 visitors, up from 50,000 the year before.

“Travel to Ukraine has become cheap,” said Sergii Ivanchuk, owner of SoloEast, a company that last year shuttled nearly 12,000 tourists to the site of the infamous nuclear disaster.

“We don’t have Crimea anymore, and less and less people are interested in religion and churches,” he added. “But we have cheap beer and Chernobyl!”

In the early morning of April 26, 1986, when this area belonged to the Soviet Union, nuclear reactor No. 4 exploded during a safety test at this power plant north of Kiev. The deadly accident, initially cloaked in Soviet secrecy, spewed radioactive fallout over much of Europe. More than 115,000 people were evacuated from a 1,000- square-mile area known as the Chernobyl Exclusion Zone.

Years later, the nuclear disaster continues to stoke the world’s curiosity — thanks in part to the hit HBO miniseries “Chernobyl” and books such as journalist Adam Higginbotham’s “Midnight in Chernobyl: The Untold Story of the World’s Greatest Nuclear Disaster,” which hit shelves earlier this year.

I FIRST visited Chernobyl in late October 2016, not long before a massive silver containment shield designed to prevent radiation leaks was rolled over the crumbling sarcophagus encasing reactor No. 4. A hundred yards from the sarcophagus, our Geiger counters shot off readings several times higher than the suggested safe levels; our guide discouraged us from lingering.

Two years later, I stood in the same spot across from the infamous reactor — now covered by a shiny arch — and the levels on my Geiger counter were only slightly elevated.

I’d returned to the Exclusion Zone because this time I wanted to sleep in Chernobyl. How many people can say that?

Two-day guided tours cost $200 to $300 a person for a group of 12 and include an overnight stay in a spartan, dormlike hotel in the town of Chernobyl, about 12 miles from the reactor. Day excursions are available too. Dozens of companies run trips to the area. Tour buses, often painted with gas masks and radiation symbols, pick up customers from Kiev’s Independence Square.

I’d brought along 11 students from Syracuse University where I teach journalism — after convincing university officials and the students’ parents that our visit would be no more dangerous from a radiation standpoint than an intercontinental flight or dental X-rays.

As we passed through various checkpoints and entered the Exclusion Zone, some students were nervous. Then they met a pack of Chernobyl puppies, mainly descendants of dogs left behind by evacuees, and their anxiousness about radioactivity subsided. Many of the estimated 300 stray dogs are tagged and tracked by scientists. At night, outside our hotel, packs of dogs yelped and howled. About two-thirds of the Exclusion Zone is a wildlife reserve, populated by increasing numbers of wolves, foxes, lynxes, wild pigs, deer and moose.

Our guide, Tatiana Globa, 22, had recently taken a group into a Pripyat elementary school, only to be met by a giant moose.

“We backed out of there fast,” she said. “I was really scared. It was huge, and they can be mean.”

On our tour, Globa pointed out radiation “hot spots,” including the red forest where trees had turned red and orange. As our bus quickly moved through a section of the woods, our Geiger counters screamed warnings with rapid beeping.

We visited Pripyat’s iconic amusement park, with its faded yellow Ferris wheel and its sad, decaying bumper cars that never gave a ride to a single child; the park was set to open the week after the explosion.

There’s an enormous sense of loss touring Pripyat, as if the town’s population had been suddenly wiped out rather than resettled. A sense of grief followed us as we traipsed through some of the few villages that hadn’t been bulldozed — kitchen tables set as if the family were about to sit down — and poked around deserted schools and hospitals where firefighters were first treated. The remains of their highly radiated clothing still send Geiger counters bleeping and Globa shouting, “Don’t touch!”

We climbed inside an unfinished cooling tower, abandoned when the reactor exploded. We stared up at the immense structure, as tall as the Great Pyramid of Giza, marveling at the raw beauty of gray concrete, buttressed by steel supports, curving up until it opened to the wintry sky.

Chernobyl is a testament to the Soviet affinity for gargantuan architecture and design. An 18-foot-tall Lenin statue is still on display in the town of Chernobyl. Tucked away in the forests near the reactor is the Duga-3 radar station, a sprawling metal structure resembling a giant roller coaster. The contraption served as a listening device, an over-the-horizon radar system meant to detect if the U.S. had launched missiles targeting the U.S.S.R.

A highlight of the trip was meeting Ivan Ivanovich, 82, at the primitive-yet-cozy home he built in Parishev village. Ivanovich is one of 119 “self-settlers” who are still alive, according to Exclusion Zone officials. The settlers were allowed to return after 600,000 so-called liquidators cleaned up the roads, bulldozed toxic buildings, scraped the radiated topsoil, and buried cars and furniture.

“The level of radiation in Kiev was the same as in Parishev, so why would I stay there?” he asked.

Ivanovich is thin and stooped but offers strangers a cheerful grin — and food.

“I can cook borscht for you,” he said. “I will boil some potatoes. My potatoes are as clean as potatoes in Kiev.”

Instead, we gave Ivanovich two sacks of groceries we’d bought and said our goodbyes. Then our bus began its journey back to the Exclusion Zone exit checkpoints where we were tested for radioactive dust on metal devices that looked like subway turnstiles. We all passed.

Along the route, our driver stopped and pointed to a pale orange lynx crouched and staring at us in the snow a few yards from the road.

“We are the strangers here,” our guide said. “This is like a planet without people.”