Los Alamos Historical Society Hosts Trinity Site Guided Tour Los Alamos Historical Society News: “…magnificent, beautiful, stupendous, and terrifying. No man-made phenomenon of such tremendous power had ever occurred before. … light with the intensity many times that of the midday sun.”—Brig. Gen. Thomas Farrell, describing the Trinity Test of July 16, 1945. In the northern reaches of the Alamogordo Bombing and Gunnery Range and 220 miles south of Los Alamos, the first-ever atomic device was detonated. Now a National Landmark Historical Site located behind the fences of the vast US Army White Sands Missile Range, Trinity Site will be open Oct. 2, the first time since the pandemic.