the Story of the Amulet by Edith Nesbit

I love the Nesbits, and this one is my favourite.

In the Story of the Amulet, the children who found the psammead (sammy-ad) that could grant them wishes find an amulet in a London junk shop, that can take them anywhere in the past to look for the other half of itself. They have to hold up the amulet and say the sacred name (which is read to them by the learned gentleman in the flat upstairs) and the amulet grows into a doorway, and they walk through it to wherever in time they want to go. The stories are very exciting - for example, the time they are imprisoned in ancient Babylon, they want to escape but then they remember that Jane has the amulet and Jane is missing! Jane, who is the indiscreet youngest, is telling the Babylonian queen all sorts of fascinating facts about Edwardian London with the result that the queen says "I wish I could see your country some day." and the psammead has to grant her wish.

So some weeks later the ancient Babylonian queen visits the children in London. She is very tyrannical, unsuitably dressed and wants all kinds of things. She is not happy with London. Someone has the bright idea of taking her to the British Museum and she is very angry that so many of her precious possessions are in there. She starts to break the glass cases and take her things back and the guards throw her out, believing she should be locked up in an asylum.

Anthea took the Queen’s hand and gently pulled her away. The other children followed, and the black crowd of angry gentlemen stood on the steps watching them. It was when the little party of disgraced children, with the Queen who had disgraced them, had reached the middle of the courtyard that her eyes fell on the bag where the Psammead was. She stopped short.
“I wish,” she said, very loud and clear, “that all those Babylonian things would come out to me here—slowly, so that those dogs and slaves can see the working of the great Queen’s magic.”
“Oh, you are a tiresome woman,” said the Psammead in its bag, but it puffed itself out.
Next moment there was a crash. The glass swing doors and all their framework were smashed suddenly and completely. The crowd of angry gentlemen sprang aside when they saw what had done this. But the nastiest of them was not quick enough, and he was roughly pushed out of the way by an enormous stone bull that was floating steadily through the door. It came and stood beside the Queen in the middle of the courtyard.
It was followed by more stone images, by great slabs of carved stone, bricks, helmets, tools, weapons, fetters, wine‐jars, bowls, bottles, vases, jugs, saucers, seals, and the round long things, something like rolling pins with marks on them like the print of little bird‐feet, necklaces, collars, rings, armlets, earrings—heaps and heaps and heaps of things, far more than anyone had time to count, or even to see distinctly.
All the angry gentlemen had abruptly sat down on the Museum steps except the nice one. He stood with his hands in his pockets just as though he was quite used to seeing great stone bulls and all sorts of small Babylonish objects float out into the Museum yard. But he sent a man to close the big iron gates.

You can read this book free of charge! Here

That's my favourite chapter and it's very funny. when E. Nesbit was researching her stories she simply went to the B.M. and knocked on the door marked Curator. She made a friend of the learned gentleman who worked behind the door and then they became more than friendly, probably on a glass case. She dedicated the book to him, Dr Wallis Budge.

Because her husband was an appalling philanderer, and she didn't see why she should not, E Nesbit had a number of lovers, many of them younger than herself, and stayed friends with them even after they had married other women. I think her stories were always written with her mind on the amusement of her peer group - H.G. Wells, for example, loved them, probably Shaw too.