­ The queue outside the Colosseum is long and winding. But with aching feet and the sun burning, waiting for an hour or so to get into the ancient amphitheatre does not seem an option.

A few metres away, two young Italians dressed as gladiators or Roman legionaries are having their picture taken by an enthusiastic tourist. Surely, this is a sight no visitor to Rome should miss.

As this reporter reluctantly joins the queue, a young Englishman who has been rounding up English-speaking tourists desperate to have a look inside the Colosseum, saves the day and promptly hands them over to an Italian guide.

The lucky few include a couple from Birmingham, a guy from Oregon, a few Australians, an elderly man with a baseball cap saying "Ireland" and a few Germans who couldn't find a tour in their own language.

The guide promises a 45-minute tour around the remains of the arena that once staged "deadly gladiatorial combats and wild animal fights," as the guidebook puts it. But before anyone has time to wonder how on earth they are going to see the whole thing in such a short time, he is ushering the group up steep stairs and around the viewing areas as if they were running for their lives.

Commissioned by the Emperor Vespasian in 72 AD, the Colosseum became Rome's greatest amphitheatre, offering space for some 50,000 spectators at a time. Admission was free for everyone, the guide reminds his group, after charging 10 euros a head for the tour. But food and drink could be bought from vendors who had stalls in the visitors' ranks. Those among us with rumbling stomachs are certainly wishing those glorious food stalls back into the 21st century!

In the olden days, male visitors were allowed sit on the stairs to watch the deadly games, but the women spectators had to watch standing from the balconies at the top of the building as the gladiators ­ men fighting with swords or in Latin the gladii ­ tried to kill each other. The gladiators were usually slaves, prisoners or condemned criminals. Very rarely were they professionals.

But it was the emperor who decided whether the loser should be spared or killed by a simple thumbs up or down. Sometimes, a gladiator may have played dead only to jump up and flee as soon as the bodies had been carried out of the arena.

"But they didn't like cheating," the guide explains with a grin. So the Romans introduced referees ­ men in black togas and masks, who would prod and punch the defeated gladiators to check whether they were actually dead. If they weren't, the referees would finish them off themselves - with a hammer.

Fighting was just as brutal for the animals. Elephants would fight bulls or a pair of lions might attack each other. Children standing in alcoves around the arena often whipped the animals making them aggressive enough to fight.

"It was very similar to the bull-fighting today in Spain," says the guide, as some of the group look on sceptically.

Today, visitors can look down from the galleries into the underground rooms and corridors, where the animals were kept. A pulley was used to lift them from the underground floors into the ring. Excavation work has unearthed the remains of the caverns underneath the destroyed floor of the arena. But it's not just from there that a few bricks are missing.

The Italians have dubbed the Colosseum "Swiss cheese" because it has so many holes. Some of the gaps in the brown brickwork are deliberate. The builders needed them to attach their scaffolding in order to build higher up. Other gaps are the result of vandalism. Greedy visitors removed the bricks to get to the metal beams underneath and scavenge bits of the material to make weapons.

"You can feel the hole inside the brickwork, where the metal has been taken out," the guide says, asking some of the group to come forward to put their hand into the cavity.

The uneven shape of the building, however, has other reasons as well, the guide explains. In 442 AD, the Colosseum was damaged in an earthquake, and in the 15th and 16th centuries its ruins were used as a quarry by the popes who recycled the travertine blocks for buildings elsewhere. That gave the Colosseum its characteristic shape ­ now on every postcard.

But before anyone has time to wonder whether the building is really safe to wander around, the tour has come to an end. And while the group needs time to take a deep breath from the heat, the running around and all the information, the guide is off for his next 45- minute show.