A new enclosure is to be officially opened at London Zoo, where keepers hope gorillas will begin to breed.
Gorilla Kingdom consists of a large open island, surrounded by a moat, an indoor "gym" and a back den.
Three western lowland gorillas will live in the enclosure: Bobby, a 23-year-old male; and two females, Zaire, 32, and Effie who is 13.
The £5.3m project means that Bobby can see the sky without bars for the first time since he was captured as a baby.
Rescued from a circus in Italy in 1983, he has not yet sired any young.
End of an era
Effie, who has recently arrived from Leipzig Zoo, has already had two babies. With her slim physique, her keepers have dubbed her "the Kate Moss of gorillas".
The newcomer has been introduced to Bobby and Zaire gradually. The zoo wants to recreate the social structure that exists in the wild - where a single dominant mature male - or silverback - has a harem of about five females.
"We've seen the end of environments that are totally divorced from nature," said David Field, director of the Zoological Society for London (ZSL), which owns the zoo.
Effie is impatient to join the others outside on the island
Mr Field has a special relationship with Bobby.
As he speaks, the gorilla watches him carefully. Mr Field says the silverback notices how the keepers react to his presence, perhaps wondering if there is another "alpha male" around.
But the director asserted that gorillas were not aggressive. "There's a lot of bluff involved in their displays; it's all about bravado," he said.
Lack of space
While the silverback appears more interested in the people watching him, Zaire is busy "gardening", digging at the earth on the island.
She was born in captivity and seems to be copying what she has seen zoo staff doing. She loves to play with shoes and fabric, "especially if it's pink or red", said keeper Daniel Simmonds.
London Zoo has been criticised in the past for not having enough space for the animals it claims to conserve.
International wildlife charity Born Free would rather the zoo phased out its keeping of gorillas in captivity and invested more in wild habitat conservation.
"The Democratic Republic of Congo... has an estimated 12 million hectares of national parks and reserves, containing perhaps as many as 5,000 individuals," said Daniel Turner, Born Free's spokesperson.
But ZSL, itself a charity, argues that its zoo raises money for overseas projects.
Efforts to protect the species continue, and it is illegal now to capture gorillas in the wild, although poaching still goes on.
Baby gorillas are sold in central Africa to be kept as pets - their whole family is killed to get at the youngster.