Peace Corps volunteer and freelance journalist Chris Miller marks the quarter-century anniversary with a photo tour.

A little more than 25 years ago, in the early morning hours of April 26, 1986, Reactor No. 4 of the Chernobyl nuclear power plant exploded, releasing a radioactive cloud that spread over much of Europe and western Russia.

The general public was unaware of the disaster until the morning of April 28. Only after a group of workers at a nuclear power plant in Sweden – more than 1,000 kilometers away – noticed a spike in radiation levels did the Soviet Union acknowledge the accident.

The disaster affected the lives of millions of people, 350,000 of which were permanently evacuated from their homes in the immediately surrounding area.

A quarter-century later, the Chernobyl exclusion zone — a guarded, 30-kilometer area around the power plant – resembles a post-apocalyptic world in which nature thrives unencumbered by humans. Excursions through the area were offered for a limited time but were suspended on June 22. The following images were taken during that last June 22 tour.