This article is part of Yahoo's 'On This Day' series.

Peter Jackson’s “The Lord Of the Rings” trilogy is widely regarded as one of the best book to film adaptations of all time.

Jackson, a fan of Tolkien’s series, masterfully and meticulously approached every aspect of the film prior to its release 20 years ago, including casting.

While many actors were offered roles in the trilogy, Jackson's intense shooting schedule proved difficult for many stars to make work with their commitments.

All three of "The Lord Of The Rings" films were shot simultaneously over the course of 436 days in New Zealand.

On the day the first Lord of the Rings instalment had its world premiere exactly 20 years ago, here's a list of actors who vied for roles in Jackson's epic Tolkien adaptation.

Frodo Baggins

Before ultimately going to Elijah Wood, Jake Gyllenhaal was among the hopeful young actors vying for the lead role in Jackson’s saga.

However, Gyllenhaal called reading for the part “one of the worst auditions” of his career.

“I remember auditioning for 'The Lord of the Rings' and going in and not being told that I needed a British accent,” Gyllenhaal told the Hollywood Reporter in 2013. “I really do remember Peter Jackson saying to me, ‘You know that you have to do this in a British accent?’ We heard back it was literally one of the worst auditions.”

Gandalf

Several famous faces auditioned for the role of the Fellowship’s mentor, Gandalf.

Although he was reportedly offered a substantial paycheck to take on the role, Sean Connory turned down the part after reading the script and expressing his disinterest in the fantasy genre.

Patrick Stewart and Christopher Plummer turned down offers to take on the role of the wizard in the trilogy, before Sir Ian Mckellan.

“I still don’t quite know how Gandalf came my way,”McKellen told GQ. “I think because some of the actors who would have been offered it before me were rather put off by the idea of having to live in New Zealand for a year. ‘Where the hell is that?’ Well, more fool them.”

Aragorn

It’s hard to believe that Viggo Mortensen wasn’t the first and only choice to take on the role of Aragorn, the sword wielding protector and heir to the throne of Gondor.

Although Vin Diesel auditioned for the role, the part was reportedly offered to Daniel Day-Lewis, Russell Crowe and Nicolas Cage.

Mortensen was cast in the trilogy weeks into filming , “The Lord Of The Rings: The Fellowship of the Ring” replacing Irish actor Stuart Townsend.

Jackson reportedly didn’t feel as though Townsend lacked the confidence to take on the role, and hired Mortensen instead.

Boromir

In "The Lord Of The Rings”, Boromir (played by Sean Bean) serves as a flawed but valiant protector of the ring, who dies while protecting hobbits Merry and Pippin.

Although Bruce Willis campaigned for the part, Liam Neeson was initially offered the role of the warrior, but reportedly turned the part down because of the character’s fate in the first film.

Galadriel

While Cate Blanchett wowed audiences as the elegant “Lady of Light”, she wasn’t Jackson’s first choice for the role.

The director supposedly offered the role to “Xena: Warrior Princess” star, Lucy Lawless, however the actress became pregnant and couldn’t take on the film’s back-to-back filming schedule.

Éowyn

As the shield maiden of Rohan, Éowyn acts as a noble warrior and unrequited lover of Aragorn. Before actress Miranda Otto landed the part alongside Mortensen, the role was initially offered to Uma Thurman, who couldn’t make the long shooting schedule work with her young family.

“Yes. It was a very long time ago, and I do consider it one of the worst decisions ever made,” Thurman told Stephen Colbert in 2017. “But I had just had my first child, and I just – I don’t know, I was a little housebound… It’s really definitely a regret.”