OLYMPIA — In the early 1960s, Washington opened an archives building to safely store the state's most important documents. The building, constructed as a largely underground bunker and opened just a year after the Cuban missile crisis, served another purpose not widely publicized at the time: nuclear fallout shelter in case of attack.

Today, a series of tunnels built to evacuate state officials and staff to the safety of the bunker go largely unused or serve as utility tunnels for steam and electrical lines. But in that era of heightened fear, "the mood was hysteria," said Jerry Handfield, state archivist since 2001.

"They assumed that the Capitol would be a target," he said. "When you strike a Capitol, you cause chaos in the ability of anyone to run a war or government."

State-sanctioned bomb shelters from that time aren't unusual. Cold War-era shelters on state government property still exist in several other states, including Nebraska, Texas and New York. Fallout shelter signs still remain at the Capitol in Maryland, and Oklahoma's emergency operations center sits in a bunker 20 feet below ground. It was originally built in 1963 to ensure state government could continue to operate in case there was a nuclear attack.

Near Seattle, a fallout shelter built into the base of a bridge on Interstate 5 now serves as storage space for the state Department of Transportation.

Nearly two dozen tall trees mask the roof of the state archives building that sits flush with the road in front of the Capitol. The trees are believed to have been planted to thwart Soviet satellites, Handfield said.

Opened in 1963 and formally dedicated a year later, the building is home to the state constitution, governors' proclamations and countless other documents tied to state government and history. As a fallout shelter, it could hold as many as 510 people during an emergency.

Handfield learned about the history of the building during a tour after he was hired. Intrigued, he and a colleague starting hunting for fallout supplies and discovered a few things, including a tin still filled with hard candy. Other items meant to reflect the time period — toilet paper still in its original packaging, medication and food — were obtained from the state military department.

In 2004, he set up a small exhibit featuring those items in a corner of the building's bottom floor, some 45 feet underground. Also on display is a copy of a proclamation that was prepared by former Gov. Arthur Langlie in the 1950s in case of an attack in Seattle "causing widespread loss of life and property."

"It's a lot easier to visualize this as a fallout shelter when supplies are here that you can see and touch," said Handfield, who grew up during the Cold War and remembers diving under desks during duck-and-cover drills as a kid.

Handfield said he couldn't find documents outlining protocol for the bunker or who was to be given priority access in case of an emergency, nor did he turn up either a written list or photos of supplies.

"Either people didn't want the records kept, or they didn't think they were important," he said.

The space can be viewed during occasional tours but is otherwise closed to the public.