The world's longest multiple-arched stone railroad bridge. Of course, it's not too hard to set a record when you set your sights on such a narrow category, but the bridge is in any rate quite pretty, and worth a visit.
Sources and licences
Guide text adapted from the Wikivoyage article "Patapsco Valley State Park" by its contributors, available under CC BY-SA 4.0. Read on Wikivoyage · Contributors · CC BY-SA 4.0
