Why Baltimore Is Hesitant to Open a 100-Year-Old Time Capsule The sealed capsule was found behind a 1915 plaque at the Washington monument.

 -- The 100-year old time capsule discovered at Baltimore's Washington Monument during a restoration project is so old that officials are hesitant to even open it.

It will be moved to nearby Walters Art Museum where conservators will assess its condition and determine when it will be safe to open the box, according to the Mount Vernon Place Conservancy.

The contents may have been exposed to the monument's dampness for a century and may be in poor condition, officials said.

Designed by architect Robert Mills, the nearly 200-year-old monument was the first one to honor the nation’s first president. Work began on the monument in 1815 and ended 1829. Mills designed the larger Washington Monument in the nation’s capital years later.

The sealed copper box was behind a plaque commemorating the monument's centennial on Defender’s Day, Sept. 12, 1915.

The initial discovery was made while project superintendent George Wilk II was investigating on Oct. 16 how the plaque was attached to the wall, the conservancy said.

"I removed the plaque just enough to stick my hand behind the plaque to stick a camera back there and take a photo," Wilk told ABC affiliate WMAR in Baltimore. "In the photo showed a box so I reattached the plaque and called Dr. Humphries to let him know that there was a box in the niche behind the plaque."

"We were hoping that the plaster in the niche might give us clues as to the appearance of the original plaster in the museum room," Lance Humphries, chair of the conservancy’s restoration committee, said in a statement. "Little did we realize that there was an actual time capsule stashed behind the plaque.”

The capsule may contain copies of commemorate programs, issues of The Sun newspaper and other items, the conservancy said.

The Mount Vernon Place Conservancy has led a $5.5 million restoration of the monument since January.