After more than three years of work, one of the USA Pacific Northwest's busiest airports is set to reopen its main terminal. And it's not going to look like your typical, industrially sterile airport . At Portland International Airport (PDX), they've spent big money aiming to bring the famed Oregon outdoors indoors.

READ MORE: These are the most Instagrammable sunset spots around the world The updated terminal is being filled with dozens of trees, thousands of other plants, streams of natural light and a wooden ceiling to create an arboreal atmosphere. PDX will also continue having appearances by "therapy" llamas and alpacas time to time. The $3.

25 billion ($US2.15 billion) renovation has several purposes, according to Allison Ferre, media relations manager with the Port of Portland, which runs PDX. A n important one is a better design to get people through the facility more efficiently.

"The previous terminal – multiple buildings patched together – wasn't designed for how we travel post-9/11 with TSA. Now the experience will be so much better," Ferre told CNN Travel in an email interview. But they've also put a major emphasis on making the passage through the airport less stressful with necessary stops at security and such.

READ MORE: How to visit the locations in Emily in Paris "The new terminal also uses biophilic design — bringing in the natural world — to harness its benefits like lowering travellers' stress, blood pressure, and heart rate and make it feel like a.