I always wondered what Aragorn was up to being a part of the Dúnedain, and a Ranger in the North.
Although Aragorn was only 10 years old when Bilbo visited Rivendell with Gandalf, Thorin and Company, I imagine him spying on the visitors and being curious about Erebor and tales of the Lonely Mountain. I can see him traveling all of Middle Earth and visiting Dale in disguise after Bard rebuilds the city.
So finally Aragorn sees The Lonely Mountain and glimpses Erebor in the distance.
Definitely listened to a lot of the LOTR soundtrack whilst working on this!