Infantry Regiment "Inmemorial del Rey" No. 1

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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 (775–776 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.^[1]