1975 Zenith Port Royal automatic, integrated bracelet, blue dial day-date.

Zenith is a luxury Swiss watch manufacturer founded in 1865 by Georges Favre-Jacot at the age of 22. Zenith was purchased by LVMH in November 1999, becoming one of several brands in their watch and jewellery division.
Zenith has a long reputation for the quality and precision of their watches. It is one of the few Swiss watch manufacturers that still produces their own movements in-house, including the Zenith el Primero one of the first automatic chronograph movements from 1969.