Two years ago after the brass "gnomon" pointer atop the sundial on Napier's Marine Parade was stolen and later recovered, engineers devised what they thought was a foolproof anchoring system to keep it safe.
Which worked - until 10 days ago.
The brass pointer has disappeared again, with the thieves leaving the marble top scuffed and the stainless steel bolting insert damaged.
"It is just senseless - so annoying and so frustrating," Napier City Council Parks and Reserves manager Tony Billing said, adding that over the weekend it happened the nearby gardens had also been the target of vandals and graffiti had been sprayed about.
He said whoever took the brass fitting would have spent some time at the sundial as the stainless steel bolts were high strength and would have been difficult to cut through.
"And they would have needed a fair bit of strength to get it off."
It is believed to have been taken over the weekend before last, and was spotted by a gardener cleaning up in the area the following Monday.
He called Mr Billing who in turn contacted police.
"It happened a couple of years ago so we had a new one cast - but then a couple of weeks later, lo and behold, one of the gardeners found the original one in nearby bushes."
Extensive searches of the gardens had been carried out in the wake of the latest theft but nothing had turned up.
"I don't know why they've done this," Mr Billing said, adding that although it was brass it was less than 2kg so did not have great value.
But its history did, he said.
The sundial had been set in place in 1933 - having been gifted to Napier by Mr JP Kirk, MBE.
It was part of the first stage of the gradual re-building and beautification of the Marine Parade gardens after the great earthquake two years earlier.
"But history and heritage means nothing to these vandals," Mr Billing said.
"They have no respect for anything."
In October 2005 the statue of Pania of the Reef was stolen then recovered about a fortnight later.
The replacement sundial pointer cast two years ago was now set to be installed, although engineers faced a challenge in how to repair the damaged base and to even more firmly secure it.
Police have appealed for any information about the incident.