Museum displays of Roman building material tend to be badly labelled and quickly walked past. A broken lump of wall behind glass with a card reading “concrete, 2nd century AD” gives a visitor nothing. Which is a shame, because the cut face of that lump contains most of the answer to why Roman structures are still standing.

Here is what to look for when you find one.

The wall is a sandwich, and the pretty part is the formwork

The single most common misreading is treating the visible facing as the wall. It is not. Roman walls of this type consist of a thick core of mortar and rubble, faced on both sides with a thinner skin of stone or brick that served as permanent shuttering during construction and as a finished surface afterwards.

A blacksmith, a stable boy, a soldier, a slave. These are the sort of people who almost never survive in the historical record — no monuments, no inscriptions, no chroniclers. A new exhibition at the Aquincum Museum in Budapest gives them their faces back. Titled “Once we were like you,” it runs until October 31 and puts visitors eye-to-eye with the ordinary inhabitants of a Roman city that stood on the empire’s northern edge nearly two thousand years ago.

The Roman public latrine is one of the few structures from antiquity that still makes modern visitors physically uncomfortable. A long stone bench, twenty or more keyhole-shaped openings cut into it at close intervals, no partitions, no doors, and a shallow water channel running along the floor at the feet of everyone seated. It looks less like a bathroom than like a piece of civic furniture — which is precisely what it was.