Step 1 : Introduction to the question "Who was originally cast in the role of Aragorn in "The Lord of the Rings" trilogy?"
...One of the pivotal roles in "The Lord of the Rings" trilogy is Aragorn, the man who would become king. Director Peter Jackson considered many other actors to portray this integral character before actually casting Viggo Mortensen. Originally, actor Stuart Townsend took on the role. He did two months of training in preparation and actually completed one or two days of filming before Jackson decided he'd made a mistake. Townsend was only 26 years old at the time and Jackson realized he was simply too young to pull off the role. So, Townsend was out and Mortensen took on the role, thanks to coaxing by his young son, no less. The rest of the story is cinematic history. Source: Old.Post-Gazette.com