Cell towers in Saint-Cyr-l'Ecole (Yvelines)

Most declared azimuths point outward, along a corridor or valley rather than at the centre. 3 supports are declared underground, in a gallery or a tunnel. For questions about exposure, see the exposure guide.

Declared supports include 3 underground or tunnel sites and 1 bridge or viaduct, with buildings making up most of the remainder.

Declared locations include 17-21 rue André Cordier, 34 Bis Rue du Docteur Vaillant, 32 rue du Docteur Vaillant, 14-16 rue Gerard Philippe, 2 Rue Guy Moquet and 2 Rue Emile Zola.

10 systems were switched on in the past 12 months. ANFR has approved one new site that is not live yet, plus additions on 2 existing masts. New: Bouygues Telecom (4G and 5G) at 1 Avenue du Colonel Fabien. 5 Bouygues Telecom 5G transmitters are listed as technically operational — installed, but not yet declared commercially in service.

8 of the 13 masts are rooftop-mounted. The tallest support is 33 m at 2 Rue Guy Moquet (pylon). The median is 18 m, slightly below the Yvelines median of 25 m.

2017 was the busiest year, with 15 new systems, most of them 4G. Local 5G started with Bouygues Telecom in November 2020; Free Mobile followed in December 2020, SFR followed in December 2021. The oldest transmitter still listed here goes back to 1997.

Of the 13 masts in the commune, Bouygues Telecom is the only carrier on 5 masts.

3.5 GHz 5G is declared by Free Mobile on 3 of its 4 masts, Orange on 3 of its 5 masts, Bouygues Telecom on 2 of its 5 masts and SFR on 2 of its 4 masts.

2.1 km to the north-west, neighbouring Fontenay-le-Fleury has only 5 masts.

At 5 km² with 21,268 residents, the commune is dense enough that most antennas sit on rooftops rather than pylons. It is part of the CA Versailles Grand Parc (CAVGP) intercommunal grouping.

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