The Hot Metal Bridge connects the Eliza Furnace (Jail) trail
with the trail on the south side of the Monongahela, allowing for
much longer rides!
You are looking for a magnetic key holder hidden in traditional
fashion. Due to the high bicyclist, skater, and walker use of the
trail, be on the lookout for quickly appearing muggles.
Congrats to Jengli10 for the FTF!