Even the flagpoles erected on either side of the border are part of the protracted battle of optics. When South Korea built a 99-metre flagpole in the 1980s, the North responded by building one that was 160 metres high (with a flag about 10 times the size of the one above Canberra's Parliament House). They now flap futilely at each other across the great divide.

As I take a tour to the Korean Demilitarised Zone (DMZ) from Seoul on the South Korean side, I'm aware that I'm looking at the story from just one side, literally and figuratively. The signs on the memorials, the bullet-scarred locomotive, the wooden bridge left as a monument for a potential reunification - these are the things the South wants you to see. And our guide goes to great lengths to explain why secret tunnels found underneath the border must have been built by the North and could not have possibly been done by her government.

But sitting to watch an introductory video, there's nothing to question when the voiceover speaks the greatest truth you'll hear here: "The DMZ has remained a scar of the war."

I see it for myself from the top of the Dora Observatory, a modern hilltop building with a rooftop viewing platform sporting a row of binoculars. The DMZ is immediately noticeable right in front, a vast tract of empty land strewn with landmines that crosses near the observatory and meanders into the distance, about 250km long in total.

With the binoculars, I can get a better look over to the North Korean side, where there's the city of Kaesong, home to about 200,000 people, and the closer town of Kijong-dong, home to an unknown number of people, possibly zero. It's claimed this is just a "propaganda village", made to look clean and colourful, but with nothing actually inside the shell of the buildings.

Kijong-dong is within the DMZ. However, I and the rest of my tour group are not. Despite numerous operators selling "DMZ tours" from Seoul, very few tourists go into the demilitarised zone itself, which is a mainly undeveloped stretch of land approximately two kilometres in each direction from the border (officially known as the Military Demarcation Line), its boundaries marked by high fences lined with guard towers, some of the most fortified in the world.

The only opportunity to go into the actual DMZ is a separate limited-number tour to a site called the Joint Security Area. The JSA is the series of blue buildings that straddle the border, used for important meetings (such as between Donald Trump and Kim Jong Un in 2019). But it can be closed suddenly for security reasons and has not reopened to tourists since a US soldier ran across to the North here in July.

Most visitors will instead spend their time inside an area known as the Civilian Control Zone, a secure buffer along the entire length of the southern edge of the DMZ. It's still heavily guarded by the military, with passport control and access only allowed with official escorts. And it's from here that I'll get the closest to the DMZ today, at a site called the Third Infiltration Tunnel.

"Please come back to South Korea," my guide requests jokingly as I start my descent down into the tunnel, just one of many supposedly dug by North Korea to try to reach the South for a sneak attack. It was still being made when it was discovered in 1978 about 73 metres below the surface - but by that time the North had dug more than 1.6km, including 435 metres over the border.

It's a steep walk down to the tunnel these days, then there's about 265 metres of it you can walk along with head and knees bent until you reach the first of three concrete blockades (with a window in the middle) that are designed to stop any attempts to use the passage for its original purpose. 75 metres above are probably land mines.

The regimented procedures to visit the locations within the Civilian Control Zone seem somewhat incongruous with the tourist resort known as Imjingak, where you gather before heading into the restricted area. As well as memorials and small museums, Imjingak has a theme park and a gondola that takes you to an art gallery at an old US base close to the DMZ. It's perplexing that the locals see this as both somewhat of a carnival and as a symbol of the painful ramifications from the division of the Korean Peninsula after World War II.

Our guide admits that everything about the DMZ is complicated. I've been on the lookout for propaganda from her, but what I've actually found much of the time is a melancholy as she talks about the families that are still separated by this fortified scar of war, and the decades-long attempts to find lost relatives. Someone in the group asks if she thinks there will ever be reunification.

"Honestly I don't know, it will be very difficult," she answers. "But what I do know - we need peace."

Over the decades, the Korean Demilitarised Zone has become a haven for wildlife, including bears, deer, and marten that have settled where there are no humans to harm them. Perhaps it's too optimistic to think they are an omen of things to come, but you have to leave a visit like this with a bit of hope, or what's the point?