Wikipedia
ATLAS-I (Air Force Weapons Lab Transmission-Line Aircraft Simulator), better known as Trestle, was the codename for a unique electromagnetic pulse (EMP) generation and testing apparatus built between 1972 and 1980 during the Cold War at Sandia National Laboratories near Kirtland Air Force Base in Albuquerque, New Mexico.
ATLAS-I was the largest NNEMP (Non-Nuclear Electromagnetic Pulse) generator in the world, designed to test the radiation hardening of strategic aircraft systems against EMP pulses from nuclear warfare. Built at a cost of $60 million, it was composed of two parts: a powerful Marx generator capable of simulating the electromagnetic pulse effects of a high-altitude nuclear explosion (HANE) of the type expected during a nuclear war, and a giant wooden trestle built in a bowl-shaped arroyo, designed to elevate the test aircraft above ground interference and orient it below the pulse in a similar manner to what would be seen in mid-air.
Trestle is the world's largest structure composed entirely of wood and glue laminate.