It was built as the main PTT (Postes, Téléphones. Télégraphie) telephone exchange building for that side of Paris, under the exchange name of Ségur, in the days when phone calls needed staff to plug through the copper wire line to connect callers. The building was designed and constructed specifically for this purpose, the architect being Jacques Debat-Ponsan, uncle to the veteran French politician Michel Debré. There were over a hundred such exchanges in Paris, and so the PTT had their own architecture team. What would be interesting to discover is whether this new Hilton has a telephone number starting 4734 nnnn. 734 was the Ségur exchange number (phone word SEG) and all local premises would be routed via this PTT building, and to this day a lot of local shops and restaurants around there include 734 in their telephone number.