Edinburgh

Edinburgh is two cities on two geologies: the Old Town, a medieval spine along a volcanic ridge from the Castle on its rock down the Royal Mile to Holyrood, with closes — narrow alleys — falling off either side into a tangle of stairs and stone; and the New Town, the Georgian grid of 1767 laid across the valley to the north, where the Enlightenment lived in symmetrical squares. Between them lies a drained loch turned garden; above them all rises Arthur's Seat, an extinct volcano inside the city; and every August the whole arrangement becomes the largest arts festival on Earth.

The traveller walks the Royal Mile from the Castle — the one o'clock gun, the Crown Jewels, the view — down through St Giles' and the closes to Holyrood's palace and Parliament; climbs Arthur's Seat for the city and the firth; crosses to the New Town for Charlotte Square, the galleries and the whisky bars of George Street; climbs Calton Hill at dusk for the monuments and the light; sits in the Grassmarket under the castle wall; and, in August, gives itself entirely to the Fringe, three thousand shows in every room that has a door.

The Guide's honesty: August doubles the population and triples the prices — book months ahead or come in June or September, when the light is long and the streets are yours —; the weather does four seasons before lunch, and a good coat outranks an umbrella in the wind; the hills are real hills and the closes are steep, so shoes matter; the city is walkable end to end and the buses are excellent; and Hogmanay is genuinely the world's New Year, and it sells out.