The North Korean city of Kaesong, long hidden behind one of the world's most heavily fortified frontiers, has been opened up to bus-loads of tourists from the South.
S Korean day trippers visited a waterfall near the city of Kaesong
The BBC's John Sudworth joined a group of sightseers on their trip.
There is a short announcement as the convoy of 10 buses, packed with South Korean tourists, crosses the demilitarised zone.
It makes the ground rules very clear.
"It is best if you refrain from criticising the leader of North Korea during your visit," we are told.
We are also forbidden from taking pictures out of the window, or discussing politics at all.
This is not the first time the secretive state has allowed coach parties to cross this tense border separating two of the world's largest armies.
For more than four years, South Koreans have been able to visit a special tourism zone on the east coast, Mount Kumgang.
But it is the first time a large city has been opened up in this way.
It is not that foreigners have not been able to visit places like Kaesong. But what is new is the arrival of bus-loads of South Koreans, day-trippers who have paid $200 a head for the privilege.
Despite the freezing cold, the tourism pioneers get a warm welcome.
The buses are greeted by lines of clapping North Korean workers from the special economic zone just outside Kaesong - cheap labour for the South Korean companies who invest here.
Kim Yoon Gyung left his family in North Korea during the war
But it is the tourist dollar the North is after now, and soon we are heading beyond the factories, down a road previously out of bounds, towards the city itself.
Our convoy is the only motorised transport on the wide, empty highway.
It is a colourless cityscape: Grey buildings with frosty roofs, no advertising hoardings, barely even a shop sign.
The average income here is about 5% of that back across the border, and for the South Korean passengers it is a chance to peer out at people sharing a common culture and language but living very different lives.
Eighty-year-old Kim Yoon Gyung is back in his home city for the first time in 57 years.
He left his wife and child here during the Korean war, and was unable to return.
He has not seen or heard from them since, and he half-hoped he might recognise someone today.
"It's impossible," he tells me.
"My old area has been replaced by a giant statue of Kim Il Sung, and anyway they won't let you stop and talk to anyone."
Sense of optimism
But despite the restrictions, is the visit a sign that North Korea might really be ready to engage with the outside world?
October's rare summit meeting between the leaders of the two Koreas ended in agreements for a range of initiatives to increase economic co-operation, including more joint business ventures and even a freight rail link.
Progress over the North's nuclear weapons programme is also adding to a sense of optimism.
In return for a large amount of aid, Pyongyang has allowed a team of international experts to begin the work of disabling the country's nuclear reactor.
Some Koreans believe that this is the only way to win change - through engagement.
Others accuse the southern government of naively propping up a repressive regime.
"The North just wants our money, that's all," one of the tourists tells me.
"They will not open all over the place, only a few historical places. They want to make dollars."
But his travelling companion disagrees.
"I do want to believe that these trips are a way to overcome our separation," he says.
"This has a lot of meaning to our people and I believe this can give us the energy needed to move towards reunification."
Family ties, or simple curiosity, mean South Korean tourists wanting to visit the North are in plentiful supply.
In May next year, the spectacular Mount Baekdu on the Chinese border will be added to the list of easy-to-visit destinations inside this isolated country.
The North knows it will be unable to completely shield its citizens from the hordes of far richer southern visitors, but it has no choice. It needs the cash too badly.