Luke Harding visits Tripoli’s museum, now guarded by two friendly rebels, Naiem and Islam.

Naiem told me how he and other locals liberated the museum on Sunday 21 August – the day the rebels surged into western Tripoli, and a popular insurrection erupted inside it. The Gaddafi soldiers were armed; the locals had no weapons other than a small harpoon used for fishing trips. “Gaddafi was mad. He had hid soldiers in hospitals, museums and schools,” Naiem said. “They left their clothes here and ran away.”

Not all escaped: the rebels captured two of Gaddafi’s soldiers trying to flee. One, Naiem said, admitted he genuinely liked Gaddafi. The other, however, explained that his officers had told him he wasn’t fighting fellow Libyans but was going to war against France, Britain and Nato. “He didn’t know the truth,” Islam said. Both soldiers were now in a rebel prison, their fate unclear in a city without a justice system.

In a room devoted to Sabratha – Libya’s other stunning Roman city – I found a bust of Marcus Aurelius. He had been taken out of his niche and propped carefully against a wall. Nearby was a female bust from a Roman necropolis, her expression dignified and mournful. I discovered more soldiers’ mattresses in a room of Neolithic grinding stones and panels of early Saharan rock art – their primitive strokes recognisable as palm trees.

Upstairs, an entire room had been devoted to the Green Book, Gaddafi’s balmy political treatise. The inscription in English was, predictably, glowing in its praise of Libya’s mysterious and vanished leader. The “charming” Gaddafi led an audacious coup against the “medieval monarchy” of King Idris, it said, and took the bold step in 1973 of nationalising Libya’s oil industry. Gaddafi’s Third Universal Theory was a philosophy superior to both western capitalism and Soviet communism, I learned.

The most intriguing discovery lay in the basement. Here, I found exhibits from the pre-Gaddafi era, carefully stored away, as well as King Idris’s palace furniture, smelling strongly of mothballs. There was a gilded Buddha, water pitchers, and a series of framed prints — a 19th-century French lithograph of the Bosporus, and portraits of Libyan nationalists who fought a century ago against Italian colonial rule. All had been hidden. “We have many heroes in Libya. But Gaddafi wanted to be the only one,” Naiem observed.