Sixty-nine years ago today, United States airmen dropped a nuclear bomb on the Japanese city of Hiroshima. At 8:15 a.m., the first bomb exploded over Hiroshima, killing 140,000 people. The Genbaku Dome was the only building left standing near the hypocenter of the bomb’s blast. Designed by Czech architect Jan Letzel, it was completed in 1915 and housed the Hiroshima Commercial Exhibition Hall.

Every year, thousands gather at the iconic dome, now the Hiroshima Peace Memorial, to commemorate the day that forever changed the world. Here’s a look at the dome throughout the years as the city of Hiroshima is resurrected around it.

The remains of the Hiroshima Prefectural Industry Promotion Building, known as the Atomic-Bomb Dome, in September 1945. ( AFP/Getty Images)

Young girls look at a poster near the center of the bomb drop in Hiroshima, Japan, on Aug. 5, 1949. In the background, the Industrial Exhibition Hall, enclosed by a bamboo fence, will be kept in its present state as a memorial remember of the “A Bomb.” (AP)

A souvenir shop stands in the street near the shattered dome of the Industry Hall near the center of the A-bomb blast in Hiroshima on Aug. 3, 1951. The shop is operated by Kiyoshi Yoshikawa, who was injured in the blast. (Kyodo via AP)

A general view of the crowd gathered at Hiroshima’s Peace Memorial Park on Aug. 6, 1954, for ceremonies marking the ninth anniversary of the first atomic bomb used in warfare. (Yuichi Ishizaki/AP)

On Aug. 2, 1955, as the new Hiroshima nears the 10th anniversary of the blast on Aug. 6. (AP Photo)

Crowds jam the area of the atom bomb memorial, center, at ceremonies marking the 18th anniversary of the atom bomb attack on the city, Aug. 6, 1963. At top center is the gutted dome that has been maintained as it was left by the attack. Light towers behind dome are those of a newly constructed baseball park. (AP)

Thousands gather on Aug. 6, 1965, at the memorial to the victims of the first nuclear weapon to be used in war. In the background is the skeleton of Hiroshima’s old industrial exhibition hall. It is the only structure preserved from the ruins of a city that has been totally rebuilt. (AP)

The dome was reinforced by Japanese architectural specialists in 1970 to be preserved as a grim reminder of that tragic moment. In the background a stainless steel Buddhist pagoda, a memorial for the a-bomb victims built in 1966. The pagoda enshrines Buddha’s ashes dedicated by Ceylonese Buddhist association. (AP)

Hiroshima in 1970, 25 years after the bomb. (Max Desfor/AP)

Citizens demonstrate in a “die-in” in front of the Atomic Bomb Dome while the 42nd memorial service for the bombing victims is being held at the Hiroshima Peace Memorial Park on Aug. 6, 1987. (Tsugufumi Matsumoto/AP)

Two women pass in front of the Atomic Bomb Dome in Hiroshima in 1995. (Kazuhiro Nogi/AFP/Getty Images)

Japanese volunteers light candles and place them during a 1999 service to pay tribute to the victims of the attack in Hiroshima. (Katsumi Kasahara/AP)

Japanese protesters hold anti-war banners during a candle light rally for peace in front of the A-Bomb Dome, background, in Hiroshima on Aug. 4, 2006. (Shizuo Kambayashi/AP)

A bereaved family prays for the atomic bomb victims in front of the cenotaph at Hiroshima Peace Memorial Park on Aug. 6, 2007. (Shizuo Kambayashi/AP)

Doves fly by the Atomic Bomb Dome during the ceremony to mark the 63th anniversary of the world’s first atomic bombing on Aug. 6, 2008. (Katsumi Kasahara/AP)

People walk past the A-Bomb Dome near Hiroshima Peace Memorial Park on the eve of the 66th anniversary of the Hiroshima atomic bombing, on Aug. 5, 2011, in Hiroshima. (Kiyoshi Ota/Getty Images)

People release paper lanterns on the Motoyasu river facing the gutted Atomic Bomb Dome in remembrance of atomic bomb victims on the 67th anniversary of the bombing of Hiroshima, on Aug. 6, 2012. (Kyodo via Reuters)

The Atomic Bomb Dome is silhouetted at sunset in Hiroshima on Aug. 5, 2013. (Shizuo Kambayashi/AP)

Related: Hiroshima remembrances