In the early 1940s, the United States feared what might happen if German physicists harnessed nuclear energy to build a bomb. In response, the nation’s best scientists and engineers convened with the goal to construct the world’s first nuclear weapon. The secret military project was called the Manhattan Project, and research and production sites were opened in Oak Ridge, Tennessee; Hanford, Washington; and Los Alamos, New Mexico.

In 1945, the atomic bombings of Hiroshima and Nagasaki helped end the war. Now, 70 years after World War II, Smithsonian reports that the National Park Service and the Department of Energy will preserve the three research sites and turn them into a national park.

The Manhattan Project National Historical Park will “share with the world the story of one of America’s most transformative scientific discoveries that fundamentally altered the course of the 20th century,” U.S. Secretary of the Interior Sally Jewell said in a release. “Visitors will soon be able to see the contributions of more than 600,000 Americans who played a role in this significant chapter in history. The park will also serve as a reminder that these actions and discoveries must be handled with great care for they can have world-changing consequences."

According to the Associated Press, officials say that the park "will tell the story of the three historical sites from a range of perspectives, including the cities in Japan where two nuclear bombs were dropped in 1945." Although the Manhattan Project National Historical Park was just formally established this week after being signed into law last year, Smithsonian says it’s been planned for about a decade.

Some nuclear activists aren’t pleased that it's now official. Greg Mello, who directs the anti-nuclear Los Alamos Study Group, described the park as “pure propaganda for Los Alamos National Laboratory and its enduring mission of creating weapons of global destruction.”

[h/t Smithsonian]