British Museum audio guide,
five stops, free.

Smaller than you expect, and darker. It sits in its own case in the middle of the room because the museum's own records make it the most-visited single object in the building.

Begin with what it is not. It is not black basalt, though it was long identified as that. The cut letters were rubbed with white chalk to make them readable and the surface was coated in carnauba wax against visitors' fingers, and together those two treatments turned the slab dark. Both came off in the cleaning of 1999, and what appeared underneath was dark grey granodiorite that sparkles where the crystals catch the light, with a pink vein across the top left corner. Find the vein. Geologists matched the rock to a small quarry at Gebel Tingar, near Aswan on the west bank of the Nile, and a pink streak like that is typical of the stone from there.

It is also not the whole thing. That diagonal along the top is a break. Measured against a comparable stele, the Decree of Canopus, it suggests fourteen or fifteen lines of hieroglyphs are gone, another thirty centimetres of stone, and above them a scene of the king before the gods under a winged disc.

The text itself is temple paperwork. In 196 BC the priests of Memphis issued a decree honouring Ptolemy the Fifth: he had given silver and grain to the temples, and in the eighth year of his reign, when the Nile flood ran too high, he had the excess water dammed for the farmers. In return the priests undertook to celebrate his birthday and his coronation day every year. A copy went to every temple in Egypt, in three scripts: hieroglyphs at the top, demotic across the wide middle, Greek at the bottom.

Finding it was an accident. In the middle of July 1799, French soldiers were strengthening a fort a couple of miles from Rosetta in the Nile delta, and Lieutenant Pierre-François Bouchard noticed the inscribed slab as they pulled down a wall inside it. Two years later the British took Egypt and the stone came to London under the Capitulation of Alexandria. Somebody here then painted two lines in white along its left and right edges: captured in Egypt by the British Army in 1801, and presented by King George the Third. They are still there.

Thomas Young picked out the phonetic characters that spell Ptolemaios. Jean-François Champollion completed his alphabet on the fourteenth of September 1822 and announced it thirteen days later, in the letter to Monsieur Dacier. The quarrel over the credit outlived them both. In the early 1970s French visitors complained that the museum's portrait of Champollion was smaller than the one of Young beside it; English visitors complained of the opposite. The portraits were the same size.

Egypt has asked for it back. In July 2003 Zahi Hawass, then head of Egypt's Supreme Council of Antiquities, called publicly for its return and called it the icon of our Egyptian identity; he repeated the demand in August 2022. The museum sent Egypt a full-size fibreglass copy in 2005, and in December 2009 Hawass offered to drop the claim to permanent ownership in exchange for a three-month loan. The stone is still in this case.

If you want to put your hands on one, there is a replica in the King's Library of this museum, standing without a case and free to touch, the way the original stood for visitors two hundred years ago.

Wait a moment before you decide it is a face. The eyebrows, the nose and the moustache belong to a man, but the same pieces of metal read as something else. A small bronze dragon head sits where the eyebrows meet, facing upward. Once you see it, the eyebrows become its outstretched wings and the nose its body, and it snarls at a second dragon, the long one running down the crest from front to back. There is a third head at the far end of that crest. Three dragons and one man in the same few centimetres.

Then compare the two eyebrows. Each carries a row of square garnets in small bronze cells along its underside. On one side those cells are lined with hatched gold foil, which throws light back through the stones and deepens the red. On the other side there is no foil, and the garnets sit straight against the bronze. In a hall lit by fire only one brow would have glittered, and the wearer would have seemed to have a single eye. That is what the god Odin had.

The helmet came out of the ground in 1939 as hundreds of rusted fragments, from a ship-burial in Suffolk, wrapped in cloths beside the head of the body. Herbert Maryon assembled it first, between 1945 and 1946, in his seventies and, as the account goes, with the use of only one eye. In 1968 the museum decided the result was wrong, took the helmet apart, and handed it to Nigel Williams, who was in his mid-twenties. He found the new joins by ignoring the decorated fronts and studying the backs, which a rotted leather lining had left blackened and wrinkled like screwed-up paper, so that they could be matched under a microscope. He finished in 1971; that is what is in front of you.

It is in London because of an argument about gold. Under the law of the day, hidden gold and silver of unknown owner went to the crown. This helmet carries too little of either to qualify, so it belonged outright to Edith Pretty, who owned the land; an inquest on the fourteenth of August 1939 found the rest of the finds were hers too. She gave them all to this museum.

Everybody wants the man in the grave to be Rædwald, king of East Anglia. He might be. Almost all that is recorded of Rædwald comes from Bede, and the historian Simon Keynes said it would fit on the back of a postage stamp. Another scholar put it more bluntly: it may be Rædwald, or it may be Sigeberht, or any other great man of East Anglia between 610 and 650.

About twenty-two centimetres of baked clay, small enough to hold in two hands, and it was never meant to be looked at by anybody. Cyrus the Great took Babylon in 539 BC, and this was buried in the foundations of the Ésagila, the temple of Marduk and the great shrine of the city, as a deposit for the gods and for whichever king dug there next. Forty-five lines of Akkadian cuneiform survive on it, wrapped around the barrel, the first and last of them too damaged to read as more than a few words.

The text is doing several jobs at once. It denounces Nabonidus, the Babylonian king Cyrus had just deposed, as an impious oppressor of low birth. It says the god Marduk chose Cyrus. It says the people of Babylon welcomed him and that he entered the city in peace. And it credits him with putting temples back in order across Mesopotamia and sending displaced people home.

That last claim is why this small object has been argued about ever since. Biblical scholars have long read it as backing the return of the Jews from the Babylonian captivity, which the Book of Ezra attributes to Cyrus. The difficulty is that the text names only Mesopotamian sanctuaries and never mentions Jews, Jerusalem or Judea. The British Museum and most specialists in the period describe the cylinder instead as an instrument of ancient Mesopotamian propaganda, one of a long line of royal building inscriptions going back to the third millennium BC, in which a new king opens his reign by announcing reforms.

That has not slowed it down. Shah Mohammad Reza Pahlavi promoted it as the first charter of human rights, a reading most historians call anachronistic; his sister presented the Secretary-General of the United Nations with a replica; and a false translation still circulates, carrying lines the cylinder does not have, including an appeal to Ahura Mazda rather than to Marduk. Neil MacGregor, a former director of this museum, made a narrower claim for it: the first attempt we know about at running a state with different nationalities and faiths.

Now look at the object itself, because it is not one object. The main fragment is the one Hormuzd Rassam dug out of Babylon in March 1879. A smaller piece reached Yale University by way of an antiquities dealer, was published in 1920, and was not recognised as part of this cylinder until 1970. Yale sent it across in exchange for what the agreement called a suitable cuneiform tablet, temporarily in principle and indefinitely in practice, and the two halves of Cyrus's announcement were reunited in 1972.