Thomas Viaduct Obelisk?

Decided to go sight seeing today in the town we are staying in Elkridge MD. So typed in what to do in Elkridge and only three things came up. The first was Thomas Viaduct Obelisk which looked quite interesting so we all went to find it. Followed the signs and this is all I could see. Rather disappointed but love the greenery. If we have time, I might go back and try again.Thought it was a monument, did read that the Thomas Viaduct is the oldest continuously operating railroad span in North America, is also a National Historic Landmark and a Maryland Historic Civil Engineering Landmark.