'World's Loneliest Lion' Moves to Sanctuary After 5 Years in a Concrete Cell at a Closed Zoo

In August, 15-year-old Ruben took a 5,200-mile trip from a shuttered private zoo in Armenia to his new sanctuary home in South Africa

A lion left by himself at an abandoned zoo in Armenia for five years has finally found freedom at a sanctuary in South Africa.

According to the animal rescue organization Animal Defenders International (ADI), 15-year-old Ruben was the only remaining animal at a private zoo in Armenia that closed five years ago. New homes were found for the shuttered zoo's other animals, but none of these locations had room for Ruben.

As a result, Ruben spent five years in a concrete cell, where his mobility deteriorated due to malnutrition and no exercise.

"Lions are the most sociable of the big cats, living in family prides in the wild," ADI President Jan Creamer said in a statement. "So it must have been devastating for Ruben to have no contact or communication with other lions."

Fortunately, "the world's loneliest lion" got help through ADI and Qatar Airways Cargo, which arranged Ruben's 5,200-mile trip from Armenia to the ADI Wildlife Sanctuary in Free State, South Africa.

Related: How Cher Helped Save the 'World's Loneliest Elephant' and Even Sang to Him: 'It Was Life-Changing'

After a successful flight to the sanctuary in August, Ruben is acclimating to his new home in his natural environment and rehabilitating from his lonely years at the zoo. The 455-acre sanctuary houses 32 rescued lions and tigers, per ADI.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories.

"Ruben was really in trouble until Qatar Airways Cargo stepped up," Creamer added. "ADI had been funding his care in Armenia since December, and when we could find no flights for him, we feared he could be stuck there."

ADI said that Ruben was examined at a veterinary clinic in Pretoria and that his habitat at the sanctuary was built with ramps and guard rails to help the lion stay active safely while he works on regaining his mobility.

"Ruben has already started to get his roar back, his morning calls getting steadily louder as he regains his confidence," ADI shared in its news release.

"Seeing him walk on grass for the first time, hearing the voices of his own kind, with the African sun on his back, brought us all to tears," said Creamer, who added that Ruben's demeanor has been totally changed, and he is no longer fearful.

Related: 4 Orphaned Lion Cubs from Ukraine Start New Life in Minnesota

"His determination to walk is inspiring. If he stumbles or falls, he just picks himself up and keeps going. He is nothing short of heroic. Incredibly, in just a few days, his movement is already improving. We know this will be a long road and will require ongoing veterinary treatment, but the start of his new life could not have been better," Creamer added.

Those interested in contributing to Ruben's continued care can learn more atadiwildlifesanctuary.org.za.

For more People news, make sure to sign up for our newsletter!

Read the original article on People.