Mostly red, certainly a fortress with many secrets, and the heart (in a less than cordial sense of the word) of Russia, the Kremlin has a function, an architecture and a history unlike any place on earth. As with many important books, the reader will wonder why nothing like Catherine Merridale’s work (ignoring a sensational account or two, and tourists’ coffee-table volumes) has been written before. Secrecy is part of the reason: it affects even archaeologists trying to uncover the endless buried strata beneath today’s monstrous complex. There is a particular difficulty in writing about an establishment that has proved so protean and that has, in its 500-year history, undergone so many destructions and resurrections and fulfilled so many different functions, religious, political and symbolic.

The Kremlin has always been best understood by outsiders. Russian poets had to come from as far away as St Petersburg in order to appreciate the full monstrosity of what to Muscovites feels like part of the scenery. Osip Mandelstam reacted typically. On his first visit, he was fascinated by