Another good friend, a university professor, visits me for coffee the next day. The absence of identities in this report tells you all you need to know about the terror which embraces Baghdad. "I was invigilating the last exams of term in the linguistics department and I saw a mature student cheating. I walked up to him and said I believed he was cribbing. He said he wasn't. I told him I would take his papers away and he leant towards me and made it clear I would be murdered if I prevented him completing his exams. I went to the head of department. I thought he would discipline this man and take away his papers. But he talked to him and then said that he could continue the exam. My own head of department failed me completely." My professor friend loves English literature, but he has new problems.

"Many of the students are now very Islamically oriented. They want their classes taught through the prism of their religion. But what can I do? I can't teach existentialism any more because it would be seen as anti-Islamic - which means no more Sartre. These same people ask me for the religious message in Eugene O'Neill's plays. What can I say? I can't teach any more. Do you understand this? I can't teach." Since Baghdad's " liberation" in April 2003, 180 professors and schoolteachers have been assassinated in Iraq, and shortly after my professor's visit, I receive a call from one of his colleagues.

"They kidnapped old Amin Yassin and his son two days ago. We don't know where they are." Amin Yassin was not, like some of his colleagues, an ex-Baathist. He was a retired linguist who taught grammar in the English department of Baghdad University. His 30-year-old son is a secondary school teacher. The two were seized in the Khavraha neighbourhood, seven miles west of Baghdad.

On Thursday, in the an-Nahda bus station, two bombs tear 43 people to pieces - almost all of them Shia Muslims - and at the al-Kindi hospital, which also receives a bomb close by, relatives of the missing are screaming as they try to identify the dead. The problem is that the morticians can't fit the limbs to the right bodies and, in some cases, the right heads to the right torsos. I head off to the Palestine Hotel where one of the largest Western news agencies has its headquarters. I take the lift to an upper floor only to be met by a guard and a vast steel wall which blocks off the hotel corridor. He searches me, sends in my card and after a few minutes an Iraqi guard stares at me through a grille and opens an iron door.

I enter to find another vast steel wall in front of me. Once he has clanged the outer door shut, the inner door is opened and I am in the grotty old hotel corridor.

The reporters are sitting in a fuggy room with a small window from which they can see the Tigris river. One of the American staff admits he has not been outside "for months". An Arab reporter does their street reporting; an American travels around Iraq - but only as an "embed" with US troops. No American journalists from this bureau travel the streets of Baghdad. This is not hotel journalism, as I once described it. This is prison journalism.

One of the Americans, an old and brave friend of mine from Beirut days, walks over. "Have a look at this, Fisky," he says. "This is the kind of crap we get from the Americans these days - this is what they want us to write about." It is a news release from the Coalition press office, the spin doctors of the occupation troops here. "Comics Bring Barrels of Laughs to Task Force Baghdad," it says.

I drive back across Baghdad. There is a massive traffic jam because the Iraqi National Guard - the American-trained Iraqis who are supposed to save Donald Rumsfeld's career and let the US forces reduce their troop strength here - have mounted a checkpoint. Most of them are so frightened that they are wearing ski-masks over their mouths. Like every Iraqi I meet, I do not trust the Iraqi National Guard. They have been infiltrated by both Sunni and Shia insurgents and now have a nasty propensity to carry out house raids on Sunni areas, to arrest the menfolk and then to steal as much money as they can find in the house. "First they arrest my son and then they take all my jewellery," a woman complained on an Arabic satellite channel that was investigating this venal militia.

I go home and switch on my television to find the BBC reporting on an " elite" force of Iraqi troops who are receiving anti-terrorism training in Britain. And there they are, foliage attached to their helmets, leaping over hedges and cooling streams. In the Welsh mountains.

Friday night. In the heart of this vast and oven-like city stands the Green Zone, 10 square kilometres of barricaded, walled, sealed-off palaces, villas and gardens - once the Raj-like centre of Saddam's regime wherein now dwell the Iraqi government, the constitutional committee, the US embassy, the British embassy and many hundreds of Western mercenaries. Many of them never meet Iraqis. Women in shorts jog past the rose beds; armed men and women " contractors" lie by the pool. There were at least three restaurants - until one of them was blown up by suicide bombers. You can buy phone accessories in a local shop, newspapers, pornographic DVDs. For tactical reasons, the Americans were forced to include dozens of middle-class Iraqi homes inside the Green Zone, a decision that has outraged many of the householders. They often have to wait four hours to pass through the security checkpoints. Irony of ironies, the tomb of Michel Aflaq, founder of the Baath party that once included both Iraq and Syria, lies inside the Green Zone.

On Friday night, this crusader castle was bathed in its usual floodlights. I was looking up at the stars over the city when there was a dull sound and a flash of light from within the Green Zone. Somewhere not far from me, someone had launched a mortar at the illuminated fishbowl that has become the symbol of occupation for all Iraqis. Many ask what will become of it when the whole Western edifice here collapses. Some say it will become insurgent headquarters, others the next parliament. My guess is that whoever runs Iraq once the occupation collapses will turn the whole thing into a theme park. Or maybe just a museum.