"My heart is at peace. I feel quite relieved," Ai said, in an exclusive interview with CNN in Beijing. 

"Every human or citizen needs -- if they travel -- they need a passport.  And mine [was] taken away with no clear reason.  And now it's back."

The artist, modestly dressed in shorts and an untucked, buttoned-down blue shirt, spoke at the galleries in Beijing where he says he's been displaying his first solo exhibit in the country of his birth.

"I never really exhibited in China -- never really put out a show by myself," he said.

The current exhibit consists of the enormous wooden pillar and beams of a massive, four-century old family assembly hall, which Ai said he discovered collapsed into ruins in China's southern Jiangxi province.

He deliberately split the massive installation into two neighboring galleries.

"The idea is you can never see the total piece... it only either exists in your imagination or in your memory," he said, standing dwarfed beneath the old house's towering timbers.

China's art boom

The exhibit is being displayed in Beijing's "798," a sprawling neighborhood of scores of art galleries sprouted up in what was once a grim factory district.  The art hub stands as a symbol of the contemporary art boom China has enjoyed, as its economy has surged in recent decades to become the second largest in the world.

Ai's round, bearded face is the most internationally-recognized representative of China's contemporary art scene. But at home, authorities have censored and shut down much of his activity online, presumably because of his outspoken criticism of the Chinese government.

In 2011, security forces detained Ai at the airport in Beijing when he was about to fly to Hong Kong. He was subsequently jailed for 81 days, accused of tax evasion. His passport was also taken from him.

Upon his release, the artist was unrepentant. He released a music video mocking the guards and their mistreatment of him in prison, and erected security cameras that provided a live video stream of his house, in a bid to mock the extensive monitoring he was subjected to by state security.

New tolerance

In his interview on Thursday, Ai appeared far less combative. 

He said he thinks the government is showing new tolerance towards him personally, by allowing the Beijing exhibit to proceed and by lifting the de facto travel ban.

But he insisted he would not censor his critique of aspects of modern China.

He said the exhibit in Beijing had an important message.

"It represents the loss of the old China," Ai said, looking up into the wooden rafters of the old building. "The aesthetics or the morals and philosophy of the whole society has completely disappeared.  And this building represents that kind of condition."