It was around 10 years ago that Mark Mitchell was perusing an antique shop and happened upon a crucial piece of Wyoming County history.

Mitchell, president of the Wyoming County Historical Society, was sifting through the upper floor of the shop, Carriage Barn Antiques in Clarks Summit, when he came across more than 20 high-quality, panoramic photographs of the famous ‘Nicholson Bridge,’ or Tunkhannock Creek viaduct.

The kicker? The pictures, which appear to have been taken in 1913 or 1914, depict the actual construction of the massive and impressive structure.

“It’s just the good fortune of luck that something like this - the knowledge of its existence - comes to pass and we’re able to bring it home,” Mitchell said.

WCHS will host its annual open house at the intersection of Bridge and Harrison streets in Tunkhannock on May 18, from 1 to 4 p.m., and the event will serve as the perfect opportunity to debut copies of the photos that were acquired for a discounted price from Carriage Barn Antiques owner Sam Mundrake.

A photograph credit is identified on the images as Geist, Nicholson.

The photographer is believed to be Edward E. Geist of Nicholson, but local historian Richard Squier said Friday he did not have any information about how long Geist might have been in Nicholson and if he indeed had a studio there or was just documenting construction of the mammoth bridge.

Squier noted that other photographs of the bridge under construction, some taken by a photographer in Scranton and some apparently contracted for by the Delaware, Lackawanna and Western Railroad, are also in the historical society’s collection but will not be on display Sunday.

The presentation of the photographs coincides with what is likely to be a couple of years of high-publicity for Nicholson and the famous viaduct, as the fall of 2015 will mark the 100-year anniversary of the bridge opening.

While two long-time WCHS volunteers Paula Radwanski and Gina Evans couldn’t agree on whether the bridge is more historically significant than ‘The Oldest House’ in Laceyville, one thing is for certain - it is a big part of the county’s history.

Coinciding with the bridge pictures are a series of photographs from 1936 showing the flooding of the Vosburg Tunnel of the Lehigh Valley Railroad o the other side of Wyoming County in Washington Township.

Also on display will be the recently-acquired original charter for the formation of Wyoming County on April 4, 1842.

“I think that for these documents to have come back to us is absolutely a remarkable event,” Mitchell said. “They have been away for so long.”

Interestingly, Wyoming County boundaries haven’t changed in the 172 years since its formation.

In a way, Sunday’s open house speaks to the nature of history to function as a way of appreciating the value of any region.

“I think that people always have to keep in the back of their mind that what they are today, is due to what their history was,” Mitchell said.

“We have some fascinating things on exhibit this year.”

As an added feature, a display at the entrance of the building will feature family emblems from Mitchell and WCHS volunteer Kent Ward, some of which date back hundreds of years.