One enduring secret has been solved in Darwin, while another no-less-confounding mystery has opened itself up for examination.

Key points: An armoured door to a room in the former Reserve Bank building in Darwin was cracked open by locksmiths after two decades

An armoured door to a room in the former Reserve Bank building in Darwin was cracked open by locksmiths after two decades Two locked safes were found inside, as well as an old record book revealing details of how the bank used to operate

Two locked safes were found inside, as well as an old record book revealing details of how the bank used to operate A former employee of the Reserve Bank remembers working in the room, and says it was used to house archives and stationary

Inside the dusty guts of the CBD's ex-Reserve Bank building — which was also a United Nations headquarters in a previous incarnation — an armoured door that had been kept locked to the public for decades was finally cracked.

A pair of locksmiths sweated over the task for more than two hours until the break finally came: they were in.

A hive of eager journalists swarmed into the room to be presented with a reality nobody wanted to face — there was nothing much in there, bar a stack of outdated shelves, lightbulb boxes, an old telephone and one dead cockroach.

It was the relics of a disused "voucher room", which was used to house archives and stationery, according to Veronica Baldwin, who worked at the Reserve Bank for 22 years until its closure in 1997.

"It was one of the best jobs I ever had, very family-oriented and fun," said Ms Baldwin, who now lives in Brisbane.

"[In the room] we used to wrap our vouchers — our paperwork — up for balancing … we had very strict guidelines."

New mystery from room

One new mystery has now surfaced from the melee.

A pair of twin safes, discovered within the voucher room, had staff of Tourism Top End — the building's current occupants — scrambling to find if they had the keys.

An NT locksmith searches through keys for the safes discovered in the old voucher room. ( ABC News: Matt Garrick )

Heritage Branch director Michael Wells said the "secure cupboards" could contain some intriguing materials.

"I didn't expect those other two safes, so we'll have to see if we can get them open," Mr Wells said.

"It's not a body, it's not big enough. And probably not gold bullion, because we were able to move them around."

Record book reveals bygone bureaucracy

There was also another item that tickled the fancy of the treasure-seekers in the room.

A moulding record book showcased a glimmer of what life was like working in the old bank.

Michael Wells, of the NT Heritage Branch, scans a record book discovered in the former Reserve Bank building. ( ABC News: Matt Garrick )

The bureaucratic loan records showed one person, by the name of M Cohen, hadn't returned a stamp book to the office, way back in 1986.

Ms Baldwin said Mr Cohen was the bank's former security guard, who was "as honest and good as the day was sunny" and would never have taken anything intentionally.

Mr Wells described the bygone bureaucracy as "absolute pedantic" and that the book "curiously" ended at the beginning of the age of computerised record-keeping.

"My father was a bank manager, and I remember the days of manual record-keeping, and this reminds me of that era," Mr Wells said.

No sign of the actual ghost

Tourism Top End visitor centre manager Julie Lawrance said while she was "very disappointed" at the lack of hundred-dollar bill bundles, she said the room would at least provide the business with some more space.

"I think there's going to be a bit of a fight to see who actually wants control of that little space," she said.

"I think the boss might want that, because it's really quiet. As long as we don't lock the door."

Ms Lawrance said the ghost that she believed haunted the building "might be a little bit disturbed" by the room having been opened, but said she had not caught glimpse of it since it happened.