Just back from Saint Petersburg, one of the most amazing cities I have ever seen, on the trail of Mannerheim as always, and also putting together material for another book project, about the activities of Japanese spies in pre-Revolutionary Russia. By the side of the glittering River Neva, I dropped in on Alexander Nevsky, at his last resting place near the Nevsky Monastery on Nevsky Place, at one end of Nevsky Prospect, the glorious boulevard that stretches all the way across the city to the Winter Palace.

I walked the whole length of it, breathing in the ghosts of Mannerheim and Pushkin, Dostoevsky and Tolstoy, and stopped off at the Moscow Station, just off the Square of the Uprising with its soaring star-topped column, to see the schematic diagram of the Russian rail system, a hundred feet across. It is like a subway map of the gods, a to-do list for Princes in Amber, a Cyrillic alternate-universe version of the London Tube, where the East London Line terminates in Sarmarkand, and the Central Line stretches on not to Hainault, but to Alma Ata. After a name change and a switch in wheels, it continues on to Beijing and Vladivostok — and there is something wondrous about standing in a train station that will take you to the Far East. Near the Church on the Spilled Blood, I bought a copy of one of my own books in Russian, as a gift for our host Alexey.

This was where Mannerheim commenced his two-year trek across Asia as part of what the Russians called the Tournament of Shadows, a journey that took him out across the Sea of Death to the edge of the world. At a cafe near the Museum of Russia’s Secret Police, I ate a meal that would have charmed Roger Zelazny, of dumplings from the Ural Mountains dipped in smetana, and dumplings from Siberia sprinkled with dill, seeing a slow transformation from west to east. Add soy sauce and chili, and you have jiaozi. Look east from Saint Petersburg, and the next border you cross can be China’s. Or Japan’s.

It’s hard to believe this was ever Leningrad. Someone has twisted the time streams, allowing the old imperial capital of Saint Petersburg to reassert itself with a vengeance, cramming the 20th century into the shadows. Golden, double-headed eagles shine on the tops of the lamp-posts, and the former Museum of Atheism has been rededicated under its old name, Saint Isaac’s Cathedral.