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.