The crumbling sarcophagus that covered the remains of the ill-fated reactor No. 4, seen here not long before the new containment shield was rolled over the structure in November 2016.

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, stories and photos from Chernobyl continue to stoke the world’s curiosity — horses born with eight legs, giant catfish found in the waters near the plant, octogenarian “self-settlers” who seemingly thrived after returning to the Exclusion Zone, eating vegetables grown in contaminated soil. Even now, interest in Chernobyl shows no signs of ebbing. Journalist Adam Higginbotham’s book, “Midnight in Chernobyl: The Untold Story of the World’s Greatest Nuclear Disaster,” hit shelves earlier this year, and HBO’s new drama miniseries “Chernobyl” debuts May 6.