Kathmandu: the city you arrive in, and the one you organise from

Thamel is a compact grid of lanes north of the old city, and it is unapologetically a traveller district — signs in English, agencies on every corner, gear shops stacked with jackets and sleeping bags, bakeries, bars and bookshops. Purists dismiss it, which misses the point: it exists because everyone heading into the mountains needs the same dozen things within walking distance of one another, and it supplies them efficiently. You can arrange a trek, buy what you forgot, eat something familiar, and sleep, all within a few hundred metres. The noise is real and the touting is persistent but good-humoured, and both drop off sharply a street or two out. Stay here on the first visit for the convenience; consider elsewhere for the last nights, when you will want quiet.

This is the city's distinctive function and it is worth arriving with a plan for it. Trekking permits are issued in Kathmandu (and in Pokhara) rather than at the trailhead, and arranging them takes at least part of a working day — more if your dates fall near a public holiday — which is the practical reason to allow two or three days here before heading out. Agencies cluster in Thamel and vary enormously in quality; the questions worth asking are about guide certification, porter load limits, what equipment and insurance the porters are given, and what happens if someone has to descend early. Gear can be bought or rented here far more cheaply than at home, with the caveat that the market carries a great deal of convincing counterfeit branded equipment alongside genuine stock — for anything your safety depends on, buy from an established shop and expect to pay accordingly, and rent the bulky items rather than carrying them from home.

A ten-minute walk south from Thamel and the city changes register entirely. The lanes around the old bazaar are a working commercial district that has been one for centuries: brass and copper vessels in one street, cloth in another, spices, marigold garlands, and shrines set into walls at the corners with fresh offerings on them. The junctions where several lanes meet function as public squares, and this is where the city is most itself — not preserved, not curated, and completely uninterested in whether you are there. Walk it in the morning when the markets are working. Getting lost is the intended experience and the valley is small enough that it does not matter.

Thamel is the obvious base and the right one for a short first stay. The alternative worth knowing about is Patan, the second of the valley's old royal cities, a short taxi ride south across the river — quieter, more architecturally intact, with a growing set of guesthouses in restored traditional buildings and a genuinely different evening atmosphere. Boudhanath, out to the east around the great stupa, is the third option and suits visitors who want the ritual life of the place rather than the shopping. Any of the three works as a base for the whole valley, since nothing in it is more than a taxi ride away; the choice is really about what you want to hear when you step outside.

The valley traps its own air, and the result is poor air quality for much of the year, worst in the dry winter months — this is the city's least attractive feature and it is worth knowing rather than discovering. Traffic is dense, largely unregulated at the small junctions, and crossing a road is done by joining a group and moving steadily rather than waiting for a gap. Dust is constant. None of this is a reason to skip the city, but it is a reason to plan around it: walk in the mornings, retreat indoors in the afternoons, and treat a day here as tiring in a way its size does not suggest.

Thamel's restaurants cover every cuisine a returning trekker might crave, which is exactly their purpose and no criticism. The better decision is to eat at least once at a Newari restaurant — the valley's indigenous cuisine, distinct from generic Nepali food and rarely on tourist menus — and the guide to what to order is on this country's food page. Beyond the city, the rest of the valley is a series of short taxi rides: Patan and Bhaktapur, the two other old royal cities, the great stupa at Boudhanath and the hilltop one at Swayambhunath, and the temple complex at Pashupatinath. What each of those is, and why three cities in one valley each have a palace square, is covered on the valley's own guide.