Accommodation: The Fiera Campionaria is an ugly, cavernous exhibition centre two bus rides plus a long walk from St Peter's Square. Spartan hardly begins to describe the conditions. There are no showers and only 20 toilets.
The beds are laid out dormitory-style, although these may well be among the biggest dormitories known to man. One of the enormous, humid, airless halls contains 500 beds, laid out in precise, straight lines, with only a couple of feet of space between each.
Anyone with a privacy fetish should look elsewhere.
But the beds are new and clean, the folded linen is crisp and each bed comes with a pillow and blankets. Best of all, in a city fast gaining a reputation for ripping off vulnerable pilgrims, these beds come free of charge and the admissions policy requires no more than name and nationality.
By yesterday afternoon, some 1,500 grateful souls had already checked in. In the next couple of days, 5,000 are expected to lay their heads here in Fiera Campionaria alone.
"They come, sleep and go," said a civil defence volunteer, Antonio Fresi. They've come from all over Europe - France, Austria, Switzerland and Spain and above all, Poland. One estimate was that 50 per cent of Fiera Campionaria's residents were Polish.
"I would say that 90 per cent of them arrive in Rome by train, they go straight to the piazza [ St Peter's Square] and usually spend just one night here."
Few are around at this time of day. Most are in the stunningly dense, five-kilometre long queues stretching down half a dozen arteries from the square. Three men who have already done their stint are trying to rest in one corner of a hall.
They include a Polish-American from Krakow, a Spanish-Briton and a Frenchman. Piotr Wlodarczyk, a 45-year-old technical project manager with IBM, originally from Krakow, flew in from Chicago on Tuesday at 3pm and was in the square by 4pm. He was still there at 2am when they closed the basilica for cleaning and remained for the three hours during which the cold, exhausted crowd did slow hand-claps, while yelling "Aprire!" [ "Open"] every time the clock boomed the quarter hour.
The crowd was too tightly packed to allow people to sit down. It took another 1½ hours after the 5am re-opening - more than 14 hours in total - for him to see what he had yearned for.
He tells the story reluctantly, not wanting to appear to be complaining. A veteran of 26 pilgrimages to Poland's Black Madonna, he is clearly a stoutly orthodox Catholic. Each time he mentions the Pope's name his voice wavers and he has to pause.
But as for most Poles, there are several layers to his devotion.
As a student radical in communist Poland, he was arrested with others for merely preparing flags and decorations for John Paul's visit in 1983.
As usual, no one explained why they were being arrested and jailed. What was most unusual was their sudden release the next day - the result of a call from the Pope's secretary, he explains, his voice breaking.
He intends to use Fiera Campionaria as his base until Monday. Fresi, a maitre d'hotel from Sicily, one of dozens of volunteers here and one of 6,500 nationwide ready to serve when called, says they will open for as long as necessary.
No one knows what will happen to the millions of pilgrims due to arrive in the city today only to discover that they've missed last night's 10pm deadline to join the queues.
Further back towards the city, in the Circo Massimo, the ancient track where Ben-Hur style chariot races were held, the beginnings of a tent city are emerging.
Here they expect up to 50,000 visitors - mostly young people, all with their own tents - to start arriving today.
Pneumatic tents are already in place, perfectly kitted out as second-stage field hospitals, complete with triage areas, recovery and surgical beds and an intensive care unit.
Although the worst they anticipate is heat stroke, there are anaesthetists and surgeons - some not long back from Sri Lanka - and specialist emergency care nurses already in place, on secondment from the regional hospital in Catania, Sicily. There are 50 from Catania, including 36-year-old Francesco Reina, an accountant with STMicroelectronics in Sicily.
The volunteers themselves are bused in every day from Castlenuovo di Porto, a little village about 40km from here, where some are lucky enough to have a roof in the national fire department's training school and others make do with tents.
These volunteers are to be seen all over Rome, invariably cheerful, doing everything from handing out bottled water to organising beds and guiding errant walkers through traffic.
Today and tomorrow, the Circo Massimo will see a different kind of spectacle to any it has experienced before. Yesterday afternoon, enormous screens were being erected to relay images from an occasion few have any chance of seeing in reality.
"But the people here will be young and always exuberant," says Francesco Reina. "They will dance all night."