Tire Playground
A giant tire playground, which would bore only the most Nintendo DS addicted kid.
Thomas Viaduct
Avalon Area
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.
Swinging Bridge
Orange Grove Area
A 300 foot suspension walkway over the Patapsco River.