(calming cheerful music)
Since the year 2008, over half of the world's population now live in urban areas, and in high-income countries like the U.K., around 80% of us call a town or a city our home.
With cities being such a big part of our lives, it's important that we understand why they exist, what they mean to us, and how they make us feel.
For most cities, the reason why they exist is actually buried far back in history.
Let's take a look at some reasons why different U.K. cities exist.
Bristol and Liverpool developed at the mouths of rivers, as seaports, with goods brought down the river and exported to cities around the world.
London, Cardiff, and Edinburgh developed as administrative centres for government, while northern powerhouses like Glasgow and Sheffield, manufactured metal goods like knives, trains, and even ships, by making use of nearby iron-ore deposits.
This is the city of Portsmouth on the south coast of England, about 75 miles southwest of London.
We can actually trace the reasons for the city's location and natural setting back across the last 20 thousand years, as the last ice age came to an end.
Ice at the poles melted and global sea levels rose, flooding these river valleys to the east and west of where the city of Portsmouth sits today, creating Portsea Island, cut off from mainland Britain by these flooded river valleys that we call rias.
This physical geography provides a natural sheltered harbour that could easily be defended from attacks from the sea.
Portsmouth first developed as a military stronghold.
Back as far as the 9th century, Portsmouth was a centre for shipbuilding, with the first recorded warship, the Sweepstake, built here in 1497.
From the 17th century, Portsmouth became a major military base for the British Royal Navy.
But with the decline of shipbuilding in the second half of the 20th century, Portsmouth sought to develop new industries alongside the naval port.
Portsmouth Harbour Railway Station provides a direct rail link to mainland Britain, and in 1976, the M275 motorway was opened, connecting the ports directly into the national motorway network as well.
Today, Portsmouth is a major commercial port.
70% of all bananas consumed in the U.K., like this one from Costa Rica, first arrive, right here, in Portsmouth.
It's often said that around the container ports, you can find lots of interesting spiders that are brought in on the banana boats.
And every single Jersey potato actually comes through these docks.
It's an internationally connected city.
Ferries carry passengers to France, Spain, the Channel Islands, and the Isle of Wight, and cruise ships take passengers to northern Europe and the Mediterranean.
And it's the geography of Portsmouth that makes it what it is.
Portsmouth's international connections make it a major hub in the global network of travel and trade.
One of the most fascinating things about Portsmouth is that it's actually the U.K.'s only island city, with most of the population here on Portsea Island.
The physical geography of the island has limited the expansion of the city.
Portsea Island has an area of only 24 kilometres squared, but the population is over 200 thousand.
That's a population density of over eight thousand six hundred people per square kilometre.
And in fact, some areas of Portsmouth have some of the highest population densities in western Europe.
This is a common situation for island cities around the world, like Manhattan, Malé, and Hong Kong; with narrow streets, tiny gardens, tightly packed houses, and lots of high rise flats.
When I think of Portsmouth, I think of the vibrant student life on the south of the island.
A very vibrant, dense city, and island city obviously.
I think of home, this is where I've lived all my life.
I went to college and university here.
One that's changed very much over the last twenty, thirty years.
Moved away from perhaps a really heavy industrial naval based city, more diverse now.
It's the sense of being surrounded by the sea even when you don't necessarily see it.
Pretty nostalgic, makes me feel quite young again.
Emotionally very strongly tied to it, because I've been here all my life.
I think the sense of community, it's quite a small town, but everybody knows everyone.
I think people are proud of the history of the navy, as well as the shipbuilding dock yards.
Navy, both my grandfathers was in the navy, so I wouldn't have ended up in Portsmouth if it wasn't for the navy.
The football team, of course.
You can see behind me, very important to the city.
The extraordinary support for the football team, is symptomatic of a kind of local sense of pride.
It's a place that was bought by the local people, saved by the local people, and I think this is a real icon for many people in the city.
It's also hugely crowded, so everywhere you go there's people, houses, cars.
I mean, it's one of the most densely populated cities in Europe, and you do have a sense of that, but you can escape to the sea, which is just behind you and see across the Solent, and it's a busy space of sea, which is really interesting.
Small, seaside.
I think there's a sense of familiarity, a sense of coming home.
I feel quite safe here.
A sort of island mentality, but not a siege mentality, I don't think.
We're quite welcoming of people who come from elsewhere.
So talking to people here in Portsmouth, we're actually collecting qualitative data about people's sense of place, and we're beginning to understand how residents and visitors to the city feel about the place.
This strong sense of place is often called topophilia.
This is from the Greek word topos, meaning place, and philia meaning love of something.
Topophilia is something we all feel at some point.
For example, when we come home, when we hear a piece of music that we associate with a place, or when we go to our favourite holiday destination.
Here in Portsmouth, ingrained in that sense of place, is the city's military history, the sea, the pride of the people who live here, and the city's connections through its seaport to destinations around Europe and the world.
And all these aspects link back to the physical geography of the city.
These sheltered inlets bring together the land, the sea, and the people of Portsmouth.
(calming cheerful music)