Usually, razor wire on top of a prison fence is designed to keep people inside its walls.
But for Napier Prison, it is keeping people out which is the problem.
The prison, which closed in 1993 has been a tourist attraction since 2002.
But not everyone wants to pay to get in. It's been struck by a spate of attempted break-ins, the most recent last Thursday.
Manager (matron) Ali Beal said the owners, who live on site, heard the break-in because of the sheer noise of it.
The group made it over the outside stone wall of the prison, then tried to get further into the complex, towards the cells where criminals were once kept.
"They were kicking the living daylights out of our back cages and doors, and throwing rocks and yelling, and yahoo-ing and carrying on."
A group was caught on security cameras, installed due to a large number of similar experiences. The prison has reported the incident to police.
A police spokesperson said they received a report of disorderly behaviour outside the prison just after 9pm on Thursday, but had no further information.
Beal said there had probably been at least five similar break-ins in the past 18 months.
She imagined some of the cases were people doing it on a dare, or for bragging rights.
"We had some people break in about a year ago, and they really put themselves in danger to climb up drain pipes, over a fence they cut away razor wire, they had to climb over a roof to get in, and then go and kick in a window.
"They just didn't want to pay the fee, and they wanted to put it all over their social media."
Once, Beal caught kids trying to break in by climbing up the hill behind the prison, which is covered in barbed wire hidden in overgrown grass.
The site is historically significant for the region.
Prior to being a prison it was the Hukarere Pa site, providing a vantage point for Māori priests to use the stars for planting and harvesting.
There is also an urupā (cemetery), which the Crown built over when it took control of the site.
It became a prison in 1862, making it New Zealand's oldest prison.
Men, women and children as young as 8, were all imprisoned at the site, built to sleep 30, but at one stage holding over 100 inmates.
Crimes ranged from petty theft to murder.
"Their stories that they have left behind are really unique and interesting."
"There's some interesting stories and some sad stories but we have to share it with our public, so we'd rather they come in and do the tour, and take their time and enjoy it, rather than just bust on in and trample and break."
The security, with fencing and razor wire, is possibly tighter now than it was in its prison days, with multiple break-out stories.
Beal told one story, where several inmates jumped over the old wall so they could have a cigarette on the top of the bluff, as the fence was not built until 1989.
"A guard came round the corner one day, and there were like three or four inmates standing out the back of the building."
When asked what they were doing they told him "oh, we are just admiring the view boss".
The guard then made them traipse back in the same way they broke out.
"They even had a master key, if you paid into a specific bank account, owned by who knows who, you'd meet the key man and he'd let you out and just be back in by headcount."