Wellington's Trades Hall now a category 1 historic place

The scene of New Zealand's first fatal terror attack has been listed as a Category 1 historic place.

It's a historic home to trade unions and the site of the infamous suitcase bombing of 1984 - Wellington's Trades Hall is now one of the most significant buildings in the country.

In 1984, Trades Hall caretaker Ernie Abbott died after a bomb exploded in a hallway, but to this day Police have never charged anyone.

"There's no place that's more prominent in the main centres of trade unionism than Wellington Trades Hall," Trades Hall President Graeme Clark says.

Graeme Clarke and a colleague walked past that very suitcase on the day but didn't pick it up.

"Pat Kelly and I walked out of the building to go to another meeting, he would have picked it up and blown us both away had he not had his arms full of leaflets about breaking the wage freeze," Clarke said.

"They gave their lives in the service of the union movement."

Abbott's portrait hangs on a wall of remembrance, and to this day no one has been charged with his murder.

"The bombing remains an open investigation and police have sent a number of exhibits to ESR for analysis," a police spokesperson said in a statement.

It's "confident that advances in technology will help identify DNA from an offender," they added.

Saturday marks 37 years since the bombing.

The building has kept its association with unions and also used to be the Labour Party's headquarters, which helped Trades Hall meet historic status. 

"The Labour movement is where the Labour Party came from and this is the home of the Labour movement in Wellington," Deputy Grant Robertson told Newshub.

It's celebrating nine decades of union history in the heart of the capital.