I am back in Porto, my fourth glorious visit in five years: half a decade of understanding the funky wackiness of northern Portuguese food, half a decade of giving myself over entirely to the unusual aesthetic of Port wine. But, more important in many ways, it has been half a decade of watching one of the world’s greatest luxury hotels come into existence (I toured the construction site), and then into its own (I’ve now stayed three times). It is a place to which I will forever wish to return.