Infantry Regiment "Inmemorial del Rey" No. 1
| Infantry Regiment "Inmemorial del Rey" No. 1 | |
|---|---|
| Regimiento de Infantería Inmemorial del Rey no. 1 | |
Coat of Arms of the King's Own Immemorial 1st Infantry Regiment | |
| Active | 1248–present (776–777 years) |
| Country | Spain |
| Branch | Ejército de Tierra |
| Type | Grenadiers/Fusiliers |
| Role | Honor Battalion – Public Duties Support Unit – Security/Administration Service Unit – Engineering Support Band Unit – Music |
| Size | 4 battalions |
| Part of | Army Headquarters |
| Garrison/HQ | Madrid |
| Commanders | |
| Commander in Chief | HM The King |
The Infantry Regiment "Inmemorial del Rey" No. 1 (Spanish: Regimiento de Infantería Inmemorial del Rey no. 1) is the senior regiment of the Spanish Army, and is considered the oldest still active military unit in the world.