In the next part of our Abandoned PA series, we're going to the Gettysburg National Military Park.There are plenty of historical sites there, but News 8's Matt Barcaro found one you might not know about. It wasn't a part of the original battlefield, but the scars from it are still there.The Gettysburg battlefield is probably one of the most looked-over lots of land you'll find anywhere. Tourists come from all over the world to scan the grounds as far as the eye can see."It's an amazing story that most visitors don't associate with the battlefield," said Jason Martz, with the Gettysburg National Military Park.But there's one walking trail on the battlefield that is a piece of history itself. You just have to know where to find it."This is often something that takes a lot of people by surprise," Martz said.That's mainly because there are no signs or any indication that the trail was once a trolley line."It was tourism. It was tourism then as much as it's tourism today. It just took a different form," Martz said.Starting in the late 1800s, just a few decades after the Battle of Gettysburg, the Gettysburg Electric Railway shuttled tourists from town to the battlefield – which, at the time, featured a dance hall, photography studio and other attractions."This was an alternate way to get here and to get a lot of people down here quickly," Martz said.The trolley line was abandoned in 1916, and the rails pulled out after the government successfully used one of the very first cases of eminent domain to take the land from the railway to preserve it for historical purposes.The trolley line's bed is now a walking trail. It runs behind the parking lot to Devil's Den and up to the wheatfield, where it disappears. You'll notice it, though, because it runs in a straight line."Once you know where to look, it's obvious. It sticks out like a sore thumb," Martz said. The remaining one-mile section of the old trolley line is on the official park map as a walking trail.And a reminder: The park is expecting a lot of tourists this summer, as it marks the 160th anniversary of the Battle of Gettysburg in July.Abandoned PA seriesAbandoned silver mine is a treasure hidden under a hill.This feat of engineering has been abandoned for nearly 130 years.Secret WWII POW interrogation camp has been forgotten in a state forest.Abandoned town was wiped off the map by ice jam flood.