At one point, it was negotiations over the tiny British territory of Gibraltar that almost derailed the process, with Spain threatening a veto if it couldn't get its conditions met.

It may seem odd that a small patch of land - only slightly larger than Canberra's Parliamentary Triangle - could have such a large impact. But this territory on the edge of Spain and the tip of Europe is a destination full of quirks.

When I first start exploring, I find it a bit hard to define. British pubs... that serve tapas? And I'm driven loco by the local unofficial language called 'Llanito' that's based on Spanish but also has words from English and other Mediterranean dialects.

Even arriving is bizarre. The main road into town intersects with the airport's runway, meaning cars wait for you to land, then you end up driving (or, because it's not far, walking) back across the runway to your hotel.

Gibraltar may come under the jurisdiction of the UK (you can tell by the iconic red British phone boxes!) but it has a decidedly southern European atmosphere. Public squares with their colonial architecture are empty during the heat of the day but bustle with people eating and drinking as the evening cools down.

One night in the main square, I try the famous local dish called 'calentita'. It's a rather plain food that looks like a baked pancake and is made from chickpea flour, water, and olive oil. It may not be the most flavoursome meal but calentita is a food of necessity for a territory with almost no agricultural land, often cut off by military sieges throughout history.

If you're wondering why there's been so much conflict over Gibraltar, you need only look around. From here, you can see Africa on the other side of the entrance to the Mediterranean Sea. It means no ship could pass through without being spotted... and attacked, if necessary.

There's one main reason why the location been so defendable against the attempted invasions over the centuries. And it's the same thing that's unavoidable as a visitor - the Rock of Gibraltar.

This hulking 426-metre-high mountain dominates the landscape here and contains some of the territory's greatest mysteries.

Take for instance the labyrinth of tunnels that go for more than 50 kilometres within the rock. I walk through the few kilometres that are open to the public - but it's the ones you can't access that are fodder for conspiracy theorists.

One rumour says they contain bunkers protected from radiation where the Royal Family would be brought in case of a nuclear attack. (I tend to think the Queen would prefer somewhere with better cocktails.)

A story the locals prefer to believe is of a secret natural tunnel from within the beautiful St Michael's Cave, all the way to Morocco. How else could there be African macaques in Gibraltar, they ask?

It's true that it's strange to see wild monkeys in Europe but it's more likely the original ones came by boat. We do know that later ones were brought to Gibraltar by order of British Prime Minister Winston Churchill when the population had dwindled to just seven. Now there are 300 of them marauding across the rock (most of which try to grab my snacks from my hand!).

Across the rock are historical sites like the Moorish castle from the 1300s and the siege tunnels from the 1700s. And there are also wonderful walking trails along the cliffs with beautiful scenery.

I walk down to another peculiarity - a beach that had 50,000 tons of sand added to it so it could be used for sunbaking. Around the corner is Europe's southernmost mosque, a large beautiful building that was a gift from Saudi Arabia. But I can't find the place where John Lennon and Yoko Ono were married (they wed here because they didn't need to give advance notification - it's one day's notice now).

I'll admit that it's an unusual place to visit but it's the kind of place you visit because it's unusual. For the 30,000 people who live here, though, Gibraltar seems normal. It's just their home. For them, it's Brexit that's peculiar!

The only flights to Gibraltar are from England or Morocco. You can drive from Spain, although you need to pass through immigration. Gibraltar has no sales tax so shopping is very cheap. However, limited space means accommodation can be quite expensive and meals are slightly more than the UK.