Like many Canberrans Lorenzo Thomas loves spending time on the coast.

When he gets the chance he heads to Maloneys Beach, just north of Bateman's Bay.

It's a few hours away and the drive got him thinking.

"I know Canberra was built as a halfway point between Melbourne and Sydney but … why wasn't it built on the coast?" Lorenzo asked Curious Canberra.

"I'd be there right now and so would many other people living in Canberra … the lifestyle would've been so different."

Curious Canberran Lorenzo Thomas had his question answered by historian Dr David Headon. ( ABC News: Sonya Gee )

Why Canberra is where it is — that's something many of you have asked us to look into.

It took federal politicians more than a decade to agree on the site for Australia's capital.

During that time, three different parliaments and two royal commissions looked into the matter. There were tours of possible sites and multiple ballots before the location was finally settled.

So, we can be forgiven for not knowing exactly why the capital ended up where it did.

But looking back a few solid — and surprising — reasons emerge.

The 100 mile rule

Canberra's location was determined, in part, by section 125 of the Constitution:

"The seat of Government of the Commonwealth … shall be in the State of New South Wales, and be distant not less than one hundred miles from Sydney."

"That's the reason," said Geoffrey Sherington, an Emeritus Professor from the University of Sydney, who wrote a thesis on the selection of a national capital site almost 50 years ago.

"Because of the Constitution saying it must be a hundred miles radius out of Sydney, the coast was virtually cut out."

Getting to this point involved a good amount of political posturing.

"[Premier of NSW] George Reid pulled all the premiers of the colony together and said, 'Look lads, if you want NSW in this federation, we get the capital,'" Canberra historian Dr David Headon said.

"Then you get not only the Victorian politicians but the very clever South Australians who said, 'Righto then, we'll agree with that … but only if the capital is at least 100 miles from Sydney. It can't be Sydney."

The capital had to be at least 100 miles (or 160km) from Sydney, which ruled out a handful of coastal locations. ( ABC News: Ryan Kerlin )

The politics didn't stop there.

In 1904 Dalgety almost became the capital of Australia.

"Of course, they [the Victorian politicians] wanted it as close to the Victorian border as they could possibly get," David said.

"The NSW politicians were aware of that, so they weren't going to let it be one metre further than a hundred miles from Sydney."

Five other factors that played a part

The tussle between Sydney and Melbourne for the capital is pretty well known.

But there were a bunch of other factors — involving rats, cannons, and the beginnings of the White Australia Policy — that came into play.

Fear of disease

A year into the search for a federal capital, a deadly rat plague hit Sydney.

The University of Sydney's Medical School identified ports as one of the major culprits, "ships imported wave after wave of infection."

A bubonic plague hit Sydney in 1900. Rats carried the disease and professional rat catchers attempted to stop the spread. ( Supplied: State Library of New South Wales )

"The world — and Australia in particular — was going through a period where disease was rife, caused usually by rats," David said.

"The feeling was you head inland to get away from the worst excesses of plagues."

Enemies at sea

A line of warships make their way through Sydney Harbour for the International Fleet Review in 2013. ( ABC News: John Donegan )

There were other dangers that could arrive by sea.

"So many cities in the world had been subject to ships coming in and … blasting away with a cannon," David said.

"If you go inland that's impossible, you've taken that out of the equation, which is self-evidently true."

For those in the know, Canberra does have a port — a few hundred kilometres away in Jervis Bay.

The freezing cold was seen as a plus

Next time you're tempted to complain about the cold, just think, it could be making you smarter. ( ABC News: Siobhan Heanue )

On a lighter note, apparently the capital was meant to be cold.

David quoted a politician better known for bringing prohibition to Canberra, when it was finally open for business.

"King O'Malley famously said, in defence of Bombala as the national capital … that 'The history of the world shows that cold climates produce the greatest geniuses.'

That comes into it really, really strongly, the cold climate myth," David said.

Even our questioner, Lorenzo, admits that a capital by the sea may have had an impact on federal politics.

"[Politicians would be] probably more laid back," he joked.

Water

A promotional pamphlet for Dalgety lists "unlimited water supply" as its top attribute. ( ABC News: Sonya Gee )

Canberra's access to water was factored into its location, just not in the way our questioner had hoped.

"It was water supply rather than being near the water," Professor Sherington laughed.

The reason? To protect the growing city from drought.

Charts held by the National Archives of Australia show that the rainfall of potential sites was monitored closely.

And that in turn explains our award-winning drinking water, and our strangely-shaped border.

A White Australia

The Immigration Restriction Act was passed in 1901 and became the basis of the White Australia Policy. ( Supplied: National Archives of Australia )

Our Curious Canberran found this next suggestion, from historian David Headon, especially intriguing.

Before the 100 mile rule was established, a location in Queensland that met the NSW and South Australian borders was floated.

"There isn't much at Cameron Corner but that was put forward seriously in 1894 where ... a whites-only capital would happen," he said

"What they were looking for was an isolated place where they could start from scratch and do what they wanted."

And here's why we'll never stop asking the question

Site inspections, written reports and numerous ballots ultimately determined where the federal capital would be. ( Supplied: The National Library of Australia )

"It's a very complex story," Lorenzo said, after hearing the answer to his question.

And even though we've done our best to spell it out here, the question of why Canberra is where it is will probably live on.

That's because it's not just a question about where it was built but why it exists at all.

"You've inherently got a prejudice that some people in the rest of the country have against their national capital — the United States had that for a long period," David said.

Some call it capital bashing.

Still, the historian believes it's an origin story Canberrans should be proud of.

"I love the fact that you can't give a simple answer ... it's a great story," he said.

"That's the thing we often forget," Amy Lay, a curator at the National Archives of Australia, said.

"The amount of planning, logistics, engineering, surveying that's gone into the whole idea to come up with a location like Canberra was really, really detailed and intense."