LOUISVILLE, KY. (WHAS11) - A major sewer project is digging up fascinating parts of Louisville's past. Construction workers recently found cobblestones and trolley tracks lining Story Avenue that date back more than a hundred years.

"We were predominantly just locating utilities ahead of the main operation. We located the trolley tracks first. Upon finding the trolley tracks, the cobblestone came with it. They happen to be built together,” TSI Construction Superintendent Jason Coffman.

A sewer project to reduce overflow is now chalked full of other treasures.

"Most of our system is underground. So, whenever you dig, especially in historic areas like this, you can find whatever was buried with that history,” MSD Project Manager and Engineer Meskerem Eshetu said.

It came as a total surprise, actually causing crews to redesign parts of the project to accommodate for the new finds.

"Basically, we redesigned the entire job around the trolley tracks and the high-pressure gas main that runs down Story,” Coffman said.

Centuries ago, the granite cobblestones made their way to Louisville as ballasts on steamboats, eventually stacking up in the city's wharf. They ultimately sailed from the seas to Story Avenue to pave the early roads.

"It's pretty neat to find. It's interesting to dig stuff up that you know hasn't been seen for lots of years,” Coffman said.

Louisville's latest find is also adding a whole lot of history to one of its newest attractions. Twenty truckloads of the cobblestones have a new home at the future Waterfront Botanical Gardens.

"We will take whatever comes here because we have lots and lots of pathways, curbs, thresholds, all those kinds of things for 23 acres,” Waterfront Botanical Gardens Executive Director Kasey Maier said.

A project to move the city forward is now also preserving its past.

"It's the history. To me, it's moving to think that we'll be walking on the cobblestones that people walked on in the early 1800s in Butchertown. It's amazing,” Maier said.

The first building at the Gardens opens in 2019. Maier said the majority of the cobblestones will the front walkway off River Road, and her team is excited for that to be one of the first things guests see.