Scientific tests have shown the oldest house in Birmingham dates back to the year 1400.
The oldest part of the pub dates from the end of the 14th Century
Analysis of the timber frames of the Lad in the Lane pub in Erdington have shown it was built in the spring at the end of the 14th Century.
A historian said the dating extended the medieval history of Birmingham.
It beats by 25 years the date of the house that was previously thought to be the oldest in the city. Only some medieval churches are older.
Dendrochronology - analysing ring patterns - on timbers in the oldest part of the house found a match to known patterns from 1400.
That makes the house 25 years older than the previous oldest, the New Shipton Barn in Sutton Coldfield, and 50 years older than the BBC Restoration prize-winning Old Grammar School in Kings Norton.
It is also almost 100 years older than what was previously thought to be the oldest pub in the city, the Old Crown in Deritend.
"This shows that Birmingham has an incredible range of historical buildings," said Peter Leather, lecturer in Birmingham Studies at the University of Birmingham, who led the dating project.
"Most people think that Birmingham is an industrial city with 19th and 20th Century buildings, but this has added another piece to our medieval history."
The house would have been the home of a high status family in 1400 and was probably built by a wealthy landowner.
It is thought it became a pub in the early 1780s and has remained so ever since, previously being called The Green Man.
Current landlady Maureen Sturdy said: "We've been saying it's the oldest for years and there've been many debates over the bar.
"So to have it confirmed is just absolutely fantastic and the regulars are over the moon.
"I hope now it will become more of a city landmark."