In the heart of Bolivia lies a prison like no other, where children roam the corridors, drugs are made and sold and an inmate council hands out corporal punishment.

Welcome to San Pedro.

Sunday Night's Denham Hitchcock went inside the prison city in the centre of La Paz with Australian author Rusty Young, the man who made this place famous.

Young's book about the prison, Marching Powder, is still a bestseller after 12 years — and the closest look anyone from the outside world has had of San Pedro.

Filmed on hidden cameras, Young returned with Sunday Night for the first time since releasing his book 12 years ago.

He is infamous to the residents of San Pedro after spending four months there — some call him a friend, many do not.

View photos Marching Powder author Rusty Young More

"I am a little bit nervous that someone might want to take some kind of revenge but I am also excited because its been a while since I have been inside there and it will be interesting to see how it has changed.

"If I was in there alone I would be very, very scared."

There are guards around the outside walls and at the gates but once you go inside the inmates run the prison, it is a cheap model that the Bolivian government supports.

"They found when they put these guys in prison their families on the outside were in terrible trouble — so the families were brought into the prison," Young said.

View photos A boy plays in his 'apartment' More

The argument is that it is safer for them to be inside the prison than on the street.

"They’re safer in here, much safer here, than on the streets, fending for themselves, So it’s a big debate, they should really have hostels but they don’t have them yet," Young said.

"The children are sometimes in actual physical danger. There are a number of cases of young girls, one girl who was six was raped and killed inside the prison when the mother was off partying.

"Only two years ago a 12 year old girl was found to be pregnant."

View photos Street food is available for purchase More

Story continues