U.S. President Barack Obama visited Hiroshima on Friday, becoming the first sitting American president in history to visit the southwestern Japanese city.

The United States dropped an atomic bomb on Hiroshima on August 6, 1945, causing a massive blast wave and a firestorm that destroyed over two-thirds of the city's buildings. Tens of thousands of people were killed instantly, and many more were injured.

A lot has changed in Hiroshima since then. Barren trees have turned into green parks. The city's train station, whose exterior walls and windows were blown out, has now been transformed into a bustling hub.

On Friday, Obama and Japanese Prime Minister Shinzo Abe mourned the city's victims together in a show of unity and reconciliation between the two countries.

We have known the agony of war, Obama wrote in the guest book at Hiroshima Peace Memorial Park. Let us now find the courage, together, to spread peace, and pursue a world without nuclear weapons.

Take a look at the GIFs below, which show photos of various parts of the city taken in August 1945 and May 2016, to see how much the city has changed in just over 70 years.

Read more:

Haunting Photos Of The Everyday Objects That Survived The Atomic Bomb

Why Most Of Japan Welcomes Obamas Visit to Hiroshima

Obama Makes The Case For A Nuclear-Free World Ahead Of Historic Hiroshima Visit

I Cannot Forgive Myself for What I Did: One Mans Recollections of His Work on the Manhattan Project