I was going to write that people walk over it, but that's wrong, as it's usually roped off.

What I'm referring to is a rather marvellous curiosity of cartography underfoot as you enter the solemn State Library of NSW (aka the Mitchell Library) in Sydney.

For the past 81 years, this object has graced the library's grand vestibule drawing attention (if you pause long enough) to a golden age of exploration in the vast, and then largely unknown, southern seas

After walking among imposing classic sandstone pillars into the cool interior of the entrance hall, you suddenly stumble across one of the library's great treasures. It's not hidden, but frozen in marble.

Here, you come face-to-face with the huge marble and terrazzo reproduction of a 17th century Dutch map. Made from yellowish marble to resemble an old map, it shows what was known then about the mystery continent (Australia) inset in brass. Also depicted are small sailing ships, a spouting whale and Latin inscriptions. It is bordered by wavy "ocean" lines of mosaic tiles.

Called the Bonaparte Tasman map, it ostensibly shows the two voyages of Dutch explorer Abel Tasman (1642 and 1644). It depicts an incredible, but incomplete, chart of Australia, revealing his results of mapping western Cape York, the Gulf of Carpentaria, much of the WA coast and the southern part of Tasmania.

Evidence of these voyages largely depends on this map, as no original journals or ship logs have survived.

Particularly interesting is that the Dutch knew much about the shape of Australia well before English explorer James Cook came along 125 years later. That was in 1769-70 to chart the totally missing east coast of Terra Australis Incognita for European eyes.

The original, priceless Bonaparte Tasman chart was acquired by the Mitchell Library in 1933, six years before master craftsmen created Sydney's marble floor map as a feature for the 'new' building, opened in 1942.

The full story of getting the map involved a tip-off in 1926 from legendary anthropologist Daisy Bates, then living at the edge of the Nullarbor Plain, and the grandnephew of Napoleon Bonaparte. That, however, is a tale for another day.

But does the marble map tell the whole story? While no one doubts the authenticity of the marble floor from the map it was copied from, no one knows the date of the original manuscript. Was it compiled before 1647, or drawn even as late as the 1690s?

It was in the earlier period that explorer Abel Tasman 'found' Tasmania, New Zealand and north-west WA. But should he get all the glory?

Author Ian Burnet, who considers the marble piece to be Sydney's greatest public artwork, thinks the map is the result of the accumulated wisdom of 16 separate voyages. These were undertaken by ships from Holland's giant East India Company (or VOC) over 38 years, from 1606 to 1644 when Dutch traders dominated the East Indies (present Indonesia).

Well before the VOC went bankrupt in 1799, the Dutch were fighting off commercial rivals such as the Portuguese and Spanish in a global game to control the lucrative trade in aromatic spices such as nutmeg, mace, cloves and pepper.

Recently, there was a link between that bygone age and the port of Newcastle when the majestic 17th century replica Dutch scout ship, the Duyfken, came into harbour.

The original Duyfken (or 'little dove') was a small, fast jacht (or hunter), which visited Australia 164 years before Captain Cook. It charted 350 kilometres of west Cape York wilderness in 1606, requiring more than a little Dutch courage sailing around reef-strewn turquoise waters.

The captain and crew of the first Duyfken were the first Europeans in documented history to step onto Australia soil, although with disastrous consequences, clashing with the Indigenous people.

The stunning $4.2 million replica Duyfken, which earlier visited Newcastle in 2001 and 2006, was built in Fremantle, WA, in 1999 and has been given to the Australian National Maritime Museum in Sydney. Expect to see her cruising on Sydney Harbour in the near future. Another option had been to send her permanently to the Netherlands.

If anyone knows just how remarkable this Dutch time capsule is, it's Col Gibson, of Lake Macquarie. He was once a tour guide on board her on an early Sydney stopover. Col was so keen on the replica vessel and its story back then he even started building a ship model of Duyfken.

"What comes to mind now is that old Dutch ships did not have a wheel for the helm to steer by, but a (hidden) whip stick', he said.

This is a vertical pole, or lever, connected through the deck to the 'tiller' in an L-shaped design. The steersman was also hidden below inside a wooden cowl staring out at the sea ahead between the running feet of seamen.

Col also said that such ships were "built by eye". During ship construction, the only plans were in the master-shipwright's head.

"The Dutch at that time built quite differently from the British. The Dutch though were masters of the sea before the Brits, anyway," he said.

The lower hull of the replica Duyfken was built plank-first just as the original ship evolved by shape in the late 16th century.

"These days most wooden ships are built in a frame first, but the Dutch laid a keel first and attached planks for the sides, adding frames as it progressed. It was a learning curve for the replica ship builders (in Fremantle). They had never done one that way previously," Col said.

And forget creaking timber floors below decks. The replica Duyfken, like the original, has a solid floor of closely packed bricks for ballast. Most seamen also slept on deck in the old days as space inside was reserved for the precious spice cargo.

The 24 metre ship also has six sails and a reported four kilometres of rope. Most rope is stiff tarred hemp, shrinking with salt water to become hard, like wire.

One of the strangest things about this unique, shallow-draught vessel is that its wooden hull has no nails. It's fastened with trunnels (tree nails) or large wooden dowels. Another odd thing is that its hull is made from European oak imported from Latvia.

During the ship's construction in Fremantle, workers kept finding blue marks within the scarred timbers, indicating metal. Saws also kept breaking.

That's because the metal was from shrapnel from hand grenade fragments and bullets embedded decades before in the once young, growing trees during WWII.

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