The new gates to Jerusalem are towering great grids of steel, opened and closed by hydraulics and set in the 25-foot-high slabs of concrete - twice as tall as the Berlin Wall - that now surround the city. The gates define the limits of what the Israelis claim as their eternal and indivisible capital, greatly expanded since they conquered the Palestinian east of the city in 1967. To the south, the border runs to the very edge of Jerusalem's holy twin, Bethlehem.
The barrier cuts across the main road into Bethlehem, leaving an opening reserved solely for Jews to visit the site of Rachel's Tomb, which is itself walled off and under military guard.
The main gate is a short distance away. Palestinians and pilgrims going to the birthplace of Jesus this Christmas will emerge the other side of the army watchtowers on to an isolated narrow backstreet. Travel its length and you arrive on the Palestinian side of the wall around Rachel's Tomb, and find desolation.
Most of what the army bulldozers haven't destroyed stands abandoned, the souvenir and coffee shops closed for lack of custom after the tourists fled with the outbreak of the intifada and the Israeli army's arrival back on the streets. With the draining away of visitors and thus the city's economy - which relies on tourism for 80 per cent of its income - Bethlehem is also haemorrhaging its indigenous population, particularly the Christians.
It ceased to be a predominantly Christian town more than half a century ago, but its Greek Orthodox and Roman Catholic populations never before left at the rate of the past few years. Since the intifada broke out five years ago, more than 10 per cent of the 23,000 Christians of Bethlehem and its satellite towns have moved away. Most of them have gone abroad.
"They went because there are no jobs," said Jiries Friej. "The economy is dead, so people leave. And people don't want to live with checkpoints every day. It feels like a prison."
The Friejes are a prominent and wealthy Palestinian family - Jiries's father, Elias, was mayor of Bethlehem for 25 years until he died in 1998 - but now it is splintering. Jiries's sister, Marina, left for Canada with her husband and children two years ago. His son Rami decamped last year to New Orleans, where he opened a restaurant. It was destroyed by Hurricane Katrina, but even that didn't force him back to Bethlehem. "My sister felt she was in jail," said Jiries. "Her husband is an agricultural engineer. He had no problem finding work in Canada. They live nicely there. Why would they want to stay living like this?"
Jiries's other son, Issa, was unemployed for three years and he, too, was looking for a way to get to the United States. Then he found a job with the Palestinian Authority, which, to the annoyance of the World Bank, is the largest employer in the occupied territories. But his father fears Issa will still leave.
"My son is 26 years old. What is his future? What is there for him to do here? This is one of the Israeli plans: for the younger generation to leave. I don't want to lose my sons," he said.
In 2000, the year the Pope travelled to Bethlehem for the millennium, more than a million tourists visited the city. That same year, Jiries opened a restaurant in a four-storey building he owns in Manger Square outside the Church of the Nativity, on the site where it is said Jesus was born. He invested about £250,000 in the restaurant thinking peace was on its way.
"We opened on 1 June 2000. The intifada came in September. A week later we closed the place. All the tourists disappeared. There were 35 employees in the place, which means 35 families relied on it. It's closed to this day," he said. A short while later, the Israelis expropriated land he owned near Rachel's Tomb in order to wall off the site. Jiries ran a souvenir shop nearby but that, too, closed for lack of customers.
Many in Bethlehem hoped that the economic devastation would pass with the end of the intifada, and the number of visitors picked up in recent months. But the flicker of optimism has been dampened by the completion of the barrier around Bethlehem and the installation of the gate, which has given a sense of permanence to the isolation and the economy's free fall. The £4m crossing is daunting even for tourists, who are searched on their coaches as they enter Bethlehem. On the way back they are forced through a labyrinth of passport and security checks. (On the whole, however, the Israeli security forces do not make tourists walk through bomb-proof rooms, in the way they do the Palestinians.)
"The Israelis tell the tourists they are going to a terrorist zone," said the Bethlehem police chief, Major General Almad al-Hadar. "It scares them, when nothing has ever happened to a tourist here. If they do this to tourists, imagine how they treat people who live here. I'm a general and I need a permit to go to Jerusalem. It can take a month to get and only be valid for a day or three days or a week."
The Israeli mantra is that the wall (around and through Jerusalem it is mostly solid concrete, even if the government keeps calling it a fence) is there solely to keep out suicide bombers. The number of bombs has declined, although that is probably more the result of the change in the Palestinian leadership since the death of Yasser Arafat, and the effectiveness with which Israel has pursued Hamas and Islamic Jihad's bomb-makers.
But there is also no escaping the fact that the 425-mile barrier has a deeply political intent. It marks out an intended border and steals large amounts of land or, as Israeli law has it, "recovers it for the Jewish people". It is, ultimately, an apartheid measure, designed to pen Palestinians on the other side of the wall while their land is expropriated for the expansion of Jewish settlements. "This is going to turn Bethlehem to a ghost town," said Bernard Sabella, a sociology professor at Bethlehem University. "The Israeli plan is to have absolute separation, to cut us off from Jerusalem, to isolate us from the other West Bank towns. That will bring absolute disaster to us. In a year's time it will be absolutely impossible for people from Bethlehem to enter Jerusalem except the few with special passes."
To drive from Bethlehem to the largest Palestinian town, Ramallah, used to take about 45 minutes. It still does if you have a car with Israeli number plates. But if you are Palestinian you are now forced to take a circuitous route around the large Jewish settlement blocks next to Jerusalem and through five army checkpoints. Typically, it is a four-hour journey. "Most wholesalers are in Jerusalem, but we don't get permits to go," said Jiries. "Lots of people here have family in Jerusalem. Now they cannot go to them: they must come here."
The Israelis find it convenient to blame the Christian exodus on the Islamicisation of Palestinian society. Hamas won a majority on the Bethlehem council in local elections this year, although the mayor is always a Christian. But the residents of Bethlehem see it differently.
"What is pushing them out is not Islam, but the real economic and political problems," said Sabella. "If it were only about Islam then only Christians would be leaving, but it's Muslims, too. Christians have been leaving at a faster rate, long before Hamas won the election, because it's easier for Christians to leave. Almost 95 per cent of Christians here have family abroad and they often know foreign languages because they usually go to schools run by foreign religious orders. If you want to go to the States, you have to speak English. Christians also tend to be middle class. Leaving is not a proposition for the very poor and very rich.
"If I were a young person and I saw no future, what would I do? There's no reason to stay."
Chris McGreal is the Guardian's Jerusalem correspondent