In short
Chamonix is a narrow valley overlooked by Mont Blanc, and it is the birthplace of mountaineering: the first ascent dates from 1786, and the first Winter Olympics were held here in 1924.
The valley runs some twenty kilometres, from Les Houches in the south to Argentière and Le Tour in the north. Chamonix centre holds the shops; the upper villages are quieter and often cheaper.
Arriving and getting around
Geneva is the reference airport, about an hour and a quarter away by road; regular shuttles make the link.
The guest card issued by accommodation providers gives free access to the valley's buses and train. That is the detail that changes daily logistics: you stay at Argentière and travel without a car.
The main lifts — Aiguille du Midi, Montenvers, Brévent, Grands Montets — are booked online in high season, departure slots being limited.
What it really costs
Chamonix is expensive, winter and summer alike. The lifts are the dominant item and multi-site passes change the arithmetic considerably.
Staying at Les Houches or Argentière rather than the centre cuts the bill markedly.
When to come
July–September for walking and high mountain work, December–April for skiing.
In late August, the UTMB fills the valley for a week: accommodation saturated and paths occupied.
May–June and October–November are shoulder seasons when many lifts close.
What nobody tells you
The Aiguille du Midi climbs to 3,842 metres in twenty minutes, from a valley floor at a thousand. That abrupt altitude gain commonly causes headaches and breathlessness. It is regularly minus fifteen at the top when the valley is at twenty-five: visitors in shorts go up every summer.
The Mer de Glace is visibly retreating. Staircases have been added regularly since the 1980s to reach the ice cave from Montenvers station, and dated signs mark the descent, showing the glacier's level at each period. It is the most direct illustration of warming available to an ordinary visitor.
The Vallée Blanche is not a piste: it is a glacier route, unmarked and unsecured, travelled with a guide and crevasse equipment.