Trinity

Trinity was the code name of the first nuclear weapons test of an atomic bomb. This test was conducted by the United States Army on July 16, 1945 at a location about 35 miles (56 km) southeast of Socorro, New Mexico, at the White Sands Proving Ground, now the White Sands Missile Range.

Trinity was a test of an implosion design plutonium device. The weapon's informal nickname was The Gadget. Using the same conceptual design, the Fat Man device was detonated over Nagasaki, Japan, on August 9, 1945. The Trinity detonation produced an explosive power equivalent to the explosion of about 20 kilotons of TNT.

This date is usually considered to be the beginning of the Atomic Age.

An instrument bunker, restored to 1945 condition:

Jumbo, a two-hundred-ton cement-and-steel monstrosity, was designed to stop the bomb’s plutonium core from being tossed all over the desert in the event that the explosion failed to achieve critical mass. Oppenheimer, confident in the end that his Gadget would work, elected not to use it. It survived the atomic blast, and, although Army engineers later blew off its ends, it has proved generally indestructible.

All that remains of the tower that held the bomb aloft:

A piece of trinitite, the glassy-green mineral that covered the ground after the blast. The geologist Clarence Samuel Ross, analyzed the substance in a 1948 paper for American Mineralogist. It is no longer radioactive — or, at least, no more so than a granite countertop.