In short
Kathmandu is a valley more than a city: three historic royal cities coexist here — Kathmandu, Patan and Bhaktapur — each with its Durbar Square, its World Heritage listed palace plaza.
Thamel is the travellers' quarter, dense with trekking agencies, equipment shops and restaurants. Patan, to the south, is the best preserved for Newar architecture. Bhaktapur, to the east, is the most homogeneous and the least motorised.
Arriving and getting around
Tribhuvan international airport is the country's entry point.
Traffic is chaotic and the air heavily polluted, especially in the dry season: a mask is not an affectation in Kathmandu. Short journeys take a long time.
Trekking permits are obtained here, before setting off: a TIMS card and a national park or conservation area permit depending on the route. The Thamel agencies handle them; the rules change and should be checked with the Nepal Tourism Board.
What it really costs
Kathmandu is cheap. Most of the budget for a stay in Nepal goes on the trek: permits, guide, porter, domestic transport.
Mountain gear is hired or bought in Thamel at low prices, with uneven quality — check the seams and zips yourself.
When to come
October–November is the best season: clear skies after the monsoon, visible peaks. March–April is the second window, with the rhododendrons.
The monsoon runs from June to September: slippery paths, leeches, cancelled domestic flights. December–February is dry and cold, with snow on the passes.
What nobody tells you
The April 2015 earthquake killed nearly nine thousand people and destroyed part of the valley's monuments. Restoration has continued since: some temples are rebuilt, others still shored up. What you visit today is partly new, and the squares are not in the state shown in older photographs.
Pashupatinath is a working cremation site, on the banks of the Bagmati. It can be observed from the opposite bank; it is a funeral rite, not a spectacle, and discretion is required.
Domestic flights to Lukla or Pokhara depend heavily on the weather: allow spare days before an international return flight.