The Colosseum underground: the hypogeum, and why no ticket opens it alone

The word that gets used online is dungeons, and it is the wrong picture. The hypogeum was not a prison. It was the machine room of the largest entertainment venue in the ancient world, and almost everything down there existed to move something upward at the right moment.

The corridors. Two levels of them, arranged along a central passage with side galleries running off it. What survives is mostly brick and concrete from later rebuilds, which is why the walls do not all match: the underground was modified repeatedly across centuries of use.

The lift shafts. This is the part people remember. Vertical shafts ran up to hatches in the arena floor, worked by counterweighted hoists and capstans turned by hand below. Scenery, equipment and animals arrived in the ring from underneath, through a floor that looked solid from the seats. A reconstruction of one of these lifts has been built and demonstrated inside the building, and once you have seen where a shaft came up, the whole oval reorganises itself in your head.

The passages out. Tunnels ran from the hypogeum beyond the walls of the amphitheatre, to the gladiatorial training school nearby and to other service buildings, so that people and material could arrive without crossing the public areas.

Standing in it, the strongest impression is not grimness. It is how busy it must have been — a low, hot, noisy, tightly organised workspace directly beneath fifty thousand people who had no idea it was there.

You go down at a fixed point in the tour, usually after the guide has explained the hypogeum from the rail above, so that you arrive already knowing what the walls are. The temperature drops. The noise of the crowd above thins out to almost nothing.

The route runs along the central corridor and into some of the side galleries, with stops at the shafts and at whatever sections are open that season. It is not a long walk in distance — the building is only eighty-odd metres across at the arena — but it is slow, because the floor is uneven and because the group stops often.

Most underground tours then come back up and out onto the arena floor, which is the reason the two are sold together so often. Going from the corridors directly to standing on the deck above them is the single best sequence of the visit, and it is what the tours from $108 upward are built to do.

Two practical notes. The headroom is low in places and the lighting is deliberately dim, so phone photographs down there are rarely the ones you keep. And if the group is large, the corridors are where you notice — which is the honest argument for the small-group tour at $327 or a private guide from $519.