Banteay Chhmar, Cambodia - It's hot and I have a headache.

The sun is too bright and reflecting off the corrugated tin roofs of tiny shops. And there are so many people, it is dizzying.

Everywhere you look, throngs of people walking from home to store, store to home, milling around street vendor carts, begging for change, or sitting on plastic chairs by the side of the road silently watching it all unfold.

Sitting in this backseat of a cramped crew cab pickup truck, I'm sharing with two other guys, our backpacks, and a 16 kilogram camera.

It's 33 degrees Celsius and I'm told it's winter: The end of the rainy season. I can't imagine it could be any worse than this, so I ask our Cambodian driver what it's like here in the summer.

He looks at me through the rear view mirror.

"Hotter," he replies, focusing his smirking eyes back on the road.

No matter how tropical or humid the climate, dry humor exists everywhere.

Out the window, I see there are far too many people on the road and too many types of vehicles. Bicycles. Bicycles with motors rigged up to their frames. Motorcycles. Motorcycles with carriages rigged up to their backs. The Cambodians call those tuk-tuks: their equivalent of a taxi. Toyota Camrys and well-worn Nissan pickups. All fighting for space on the road with the cattle and chickens and men and children and women carrying woven wicker baskets on their heads.

There are no stop-lights, no stop signs. No rules or order to the roadway that I can make out, except that if you are going to pass, you have to honk.

A man on a motorcycle weaves around an old piece of farm equipment plodding down the road, then swerves awkwardly to avoid an oncoming car. The man's wife and two small children clutch on to each other's clothing, to avoid being thrown off.

It's all too much. I look in my backpack for a bottle of water. All the activity is making me nervous and nauseous.

Some of my crankiness can be attributed to the fact I'm just a few hours removed from an arduous 17 hour trans-Pacific flight that started in Atlanta, crossed the Arctic Circle, dropped me off in Seoul to catch my breath and stretch my cramping legs, and then carried me on to Siem Reap.

We're going to be here for the next 10 days shooting a documentary on human trafficking and the personal impact it has on the lives of families. Before we do that, though, we're taking a side trip to a place called Banteay Chhmar, to file a story about climate change and the effects it can have on a civilization.

Banteay Chhmar is the kind of place I didn't think still existed on Earth. An ancient ruin, it's discovered but still unknown. Built in the 12th century by the great Khmer ruler Jayavarman II, today it sits empty. Historians still don't know why the city was built or why it was abandoned. It's hard even to understand why it's still here. Just a few meters from a village with the same name, there are no tourists, no squatters and very little evidence that there ever have been.

There are only a few dozen local laborers who, under the supervision of project leader John Sanday, are working to restore the site to the point it's safe and attractive to outside visitors. The hope is, they'll be able to train locals to set up a responsible, sustainable tourist industry, where the money goes to members of the local community, not foreign investors from countries like South Korea, the United States, China, or Japan.

The city was abandoned more than 500 years ago. Sanday, who is an architect by trade and lives in Katmandu, is our guide. He tells us that scientists believe that changes in the climate coupled with political instability and an aging infrastructure. He surmises that a period of prolonged drought created water scarcity, food shortages and unrest, which forced the royal family to move south to the area which is now Phnom Penh.

When that happened, like the city's reservoirs, its wealth and economic energy also dried up.

As our truck rambled into the site, we turned onto a pathway that crossed over that same reservoir. Two giant Buddha heads made our welcome at the entrance.

I was amazed they were still there. Two minutes later we were in the main part of the city. Now I was shocked. To me, it felt like re-entering a city that had been evacuated during a bombing raid. Sanday led us around, pointing out why this gate was important, why rulers had created that massive bas relief to show their power, and how this structure had been felled by the roots of a tree. Everywhere you looked were piles of rubble. It went on for hundreds of meters in every direction.

There were large courtyards where only pillars remained. Huge rooms that opened to the sky and jungle canopy. Intricately carved doorways stood, upright and exposed, while the wall that had encased it lay in a heap. Each time you rounded a corner, or even turned your head, there was something new and breath-taking to look at and take a picture of.

My favorite part of the city, though, were faces of the Buddha, carved seamlessly into the towers of the temples, looking out over all of it. A precursor to the architecture you see on the Bayon Temple at Angkor Wat, the entire time we were there they seemed to be looking down at us, smiling knowingly, as we explored their city and pointed our cameras up to take their picture.

We spent two days there, bounding over the ruins, looking at the incredible art and architecture, taking pictures and discussing what led to the collapse of this once-powerful civilization.

When it was time to leave, and we crawled through to the old corridor made dark by dusk's fading light, I thought about the people who passed through these hallways so many centuries ago. I thought how interesting that, thanks to the potential tourism industry, their hard work then, might now bring about a new dawn in the lives of their descendents.

And as we packed into pick-up for our long ride back to Siem Reap, I was struck by another thought and smiled.

This was definitely worth the trip.

HONG KONG, China – My recent interview with Aki Ra, a Cambodian dedicated to landmine removal after being forced as a child by Khmer Rouge to plant mines, reminded me of my own close brush with unexploded ordnance.

A Cambodian woman walks past a landmine awareness sign near the Thai border in July 2007.

I was on a reporting assignment in former Khmer Rouge turf in northern Cambodia.

After hours riding on a bumpy road, nature called. We were in an area that had just reportedly been cleared of landmines and the government was resettling military families there.

Some villagers came out to greet us. We asked for a bathroom but there was none. Instead, they pointed to a path that still had a sign warning about the presence of landmines. You can never be sure if the mines are all gone, they said, so just stay on the path and find a spot along the way.

There were no trees and I juggled modesty with safety as I hesitatingly inched down the path. I turned back a few times and saw the dozen or so villagers standing on the road, watching my progress.

I finally got my business done and briskly returned along the path to our car.

But I have never forgotten that moment. It made me think of the risks that Cambodians, and others living in such heavily-mined countries - Iraq, Colombia, Afghanistan - take everyday to go about their daily lives: Tilling a field to cultivate crops, walking to school, rounding up the family's livestock or even finding a spot for a community outhouse.

As a reporter for an international news agency in the country for more than two years, I encountered many Cambodians - old and young - whose futures in one of the world's poorest countries were literally hobbled by these weapons of war.

They all made do with their challenging situations in a country where physical fitness is part of daily survival, since many Cambodians are doing some type of farming or fishing to put food on the table.

Meeting Aki Ra, who has now started his own non-profit group to rid the country of mines, reminded me how much this sad legacy of decades of conflict will continue to linger on for Cambodians until the last mine is cleared. Read the article on Aki Ra

The Khmer Rouge trial has been a harrowing story to cover. The unimaginable magnitude of the killing is breathtaking: 1.5 million, 2 million, some even put it as high as 3 million - an abstract and unfathomable number.

But it's when I'm confronted with men like Norng Champhal that the horror and terror are really drawn into sharp, brutal focus. He told me through tears of raw grief, how he was separated from his mother 30 years ago at the most notorious of the 189 torture and detention camps, Tuol Sleng or S-21.

Norng Champhal was just 8 or 9 when he was taken to Tuol Sleng prison. He is one of the few survivors.

He never saw his mother again and spent several days hearing the haunting screams of people being tortured to death. Then finally the Khmer Rouge fled, as invading Vietnamese forces approached. He frantically ran from room to room looking for his mother.

In each, he found iron bed-frames with blankets thrown over the mutilated corpses the KR had hurriedly abandoned.

He told me he peeked under one blanket, trembling as he looked. A nine-year-old boy, checking corpses to see if they were his mother. He never found her, but he thinks it's impossible she survived. He says those memories are still so fresh and clear they are still profoundly painful.

More than 14,000 people died in S-21. Only a few survived, among them Champhal.

His story is repeated across this violated land. At least a quarter of the population died between 1975 and 1979. It would be the equivalent of approximately 70 million Americans being slaughtered in just three years, eight months and 20 days.

Historians argue about the extent to which the U.S. secret bombing of Cambodia contributed to the rise of the fanatical Maoist regime.

Certainly the U.S., U.K. and others continued to back the KR long after they were ousted from the capital. But this trial will not initially dwell on U.S. involvement or the causes of the Khmer Rouge rising to power.

It will begin simply with the story of S21 and the man that put so many, including Champhal's mother, to death.

Duch, or Kaing Guek Eav, is charged with crimes against humanity and has admitted his role as Commandant of S21. Now finally Champhal may begin to get some answers about the nightmare that still casts its long and dark shadow over this traumatized country.

Watch my report on notorious Tuol Sleng and survivor Norng Champhal's recollection of the torture camp.