Cell towers in Guyancourt (Yvelines)

Most of the town's 30 masts are buildings (21); 1 camouflaged "tree" pylon make up the rest of the mix.

Declared locations include Etang du Bois Robert, Pont du Routoir, Parc D'Activite des Sangliers, Les Sangliers, La Minière and Le Pont du Routoir.

13 systems were switched on in the past 12 months. ANFR has approved 2 new sites that are not live yet, plus additions on 6 existing masts. New: SFR (4G and 5G, including 5G at 3.5 GHz) at 18 Mail des Garennes and SFR (4G and 5G, including 5G at 3.5 GHz) at 15 Rue Andréa Palladio. 17 Bouygues Telecom 5G transmitters are listed as technically operational — installed, but not yet declared commercially in service.

21 of the 30 masts are rooftop-mounted. The tallest support is 49 m at Etang du Bois Robert (pylon). The median is 22 m, slightly below the Yvelines median of 25 m.

2014 was the busiest year, with 38 new systems, most of them 4G. Bouygues Telecom opened 5G here in November 2020; Free Mobile followed in December 2020, SFR followed in December 2020. The oldest transmitter still listed here goes back to 1995.

Of the 30 masts in the commune, Bouygues Telecom is the only carrier on 9 masts.

By mast count, Guyancourt is 3rd of the 62 Yvelines towns that have five or more. With 30 masts for 29,778 residents, or 10 per 10,000, it has more masts per inhabitant than the median for those towns (7).

3.5 GHz 5G is declared by Orange on all 12 masts, Free Mobile on all 10 masts, Bouygues Telecom on 8 of its 13 masts and SFR on 5 of its 6 masts.

Voisins-le-Bretonneux lies 2.4 km to the south-west and has only 8 masts.

At 13 km² with 29,778 residents, the commune is dense enough that most antennas sit on rooftops rather than pylons. It is part of the CA de Saint Quentin en Yvelines intercommunal grouping.

Source: operator declarations to ANFR, as of October 2026. Projects that are only approved are left out of the totals.