Saint Peter's Chair Feast Day - 18 January

https://www.pope2you.net/what-is-the-vatican-throne/

Quoted from Catholic Culture [1]:

The feast of the Chair of Saint Peter at Rome has been celebrated from the early days of the Christian era on 18 January, in commemoration of the day when Saint Peter held his first service in Rome. The feast of the Chair of Saint Peter at Antioch, commemorating his foundation of the See of Antioch, has also been long celebrated at Rome, on 22 February.

[1] https://www.catholicculture.org/culture/liturgicalyear/calendar/day.cfm?date=2013-02-22