Rare indeed: The village's copy of The General Plan of Riverside is one of just three known to exist of the 2,500 lithographs printed in 1869 as promotional items for prospective buyers.Courtesy of the Riverside Historical Museum

If there’s a holy relic in the collection at the Riverside Historical Museum, it has to be the General Plan of Riverside.

Produced by the Riverside Improvement Company and created by Olmsted, Vaux & Co. in 1869 to help fuel sales for the as-yet-unbuilt community, the 26-by-32-inch chromolithograph shows the the developers’ grand plan and a pretty recognizable version of what would eventually become Frederick Law Olmsted’s village in the forest.

“It’s not really a map,” said Judith Cizek, chairwoman of the Riverside Historical Commission, which runs the museum and cares for the artifacts in its collection. “It’s a conceptual plan for what Riverside should look like.”

Since 2003, the General Plan has been displayed in a frame on a wall inside the museum in the east well house in Centennial Park. But it’s unlikely that the plan will ever be displayed that way again and, in the future, seeing it in person will be a rare treat.

The commission in late September handed the lithograph over to the folks at The Conservation Center, a Chicago business that restores and repairs works of fine art for museums and private collectors, to be evaluated and restored.

“It’s one of the most important pieces in our collection,” Cizek said, “so I thought it deserved some attention.”

The General Plan of Riverside is a rare item. In 1869, the Riverside Improvement Company printed 2,500 copies of the lithograph as promotional items for prospective property buyers in the proposed development.

But only three lithographs from that limited edition printing are known to exist — the one owned by the village of Riverside, one in the Library of Congress and one at the Frederick Law Olmsted Historic Site in Brookline, Mass.

Riverside’s lithograph was a gift from John Lewe Jr. in 1993. In 2003, it was officially accessioned, matted and framed by the Riverside Historical Commission. Since that time, the lithograph has been on display in the museum.

“The commission was concerned about damage done by light,” said Cizek. “Works on paper are only supposed to be on display for a certain amount of time.”

Ideally, said Cizek, paper should be on display for no more than 90 days at a time.

“In 1869 there were no colorfast dyes,” said Cizek. “We felt it necessary to have it checked so no further deterioration occurs on the plan.”

While The Conservation Center didn’t find any major damage to the General Plan, they did recommend a pretty thorough restoration and rethinking how the lithograph should be displayed.

The map will receive a cleaning on both sides to remove both dirt and any adhesives that may have been used in the past. Cizek said the map will also undergo “passive humidification” to help counteract any brittleness of the paper. The map will then be dried between cotton blotters and placed under weights to smooth out rippling that has occurred over the years.

In addition, some of the paper that has broken off at the edges will be reattached and a conservator will also fill in areas of the map where paper has been lost to return the surface to its original pristine condition.

“We’re trying to restore it to its original glory,” Cizek said.

Once the work is complete, the map will be mounted on archival-quality matting and placed in a custom-made portfolio.

And after all that, the General Plan of Riverside will take an extended nap in storage before it gets placed on display again.

“We want to rest it for at least 2-3 years away from light,” said Cizek.

However, anyone wishing to see the map — scholars doing research for example — will be able to do so upon request.

“We’ll make special arrangements to bring it out to show on those occasions,” she said.

According to Cizek, the work will cost about $900 to complete and the General Plan should be back in the hands of the commission by late January.