The site presents outstanding examples of mono-industrial manufacturing towns which are well preserved and still active. Le Locle and La Chaux-de-Fonds are an example of a symbiosis between the watch industry and urban development. Starting out as small mountain villages 1,000 metres above sea level, La Chaux-de-Fonds and Le Locle were shaped over a few decades by the watch industry.

At first glance the lengthy straight streets that characterise La Chaux-de-Fonds and Le Locle may seem boring and rather insignificant. But in fact they have both historical and architectural value. The street plan, the buildings and the factories that constitute the urban makeup were designed to answer the needs of a new industry that over time has come to symbolise the region.