The Riddle-Game

[Fusillade]

Excellent first riddle Fusillade, keep them coming!

Thanks! And yes, of course the answer is indeed the Last Bridge.

All pretty obvious but here's the breakdown:

1st stanza refers to Bilbo crossing over on his way to the Lonely Mountains, and Frodo's crossing bearing the ring.

2nd refers to the 3 Nazgul Glorfindel found awaiting Frodo on his way to Rivendell.

3rd refers to Aragorn, finding the green stone left by Glorfindel as a token indicating it was safe to pass.

4th is the total give-away using the Sindarin name for the Hoarwell.