Famous for its marble, in the 1st century CE the Romans were mining the quarries, which are no longer being used. There are literary references that call Ereño the “capital of the marble route”. That material can be found in numerous buildings in Urdaibai and also on the other side of the ocean.
According to historian Tomás de Goikolea, Ereño was built in the 9th century and the residents of the town may be direct descendants of the inhabitants of the Santimamiñe cave.
On 29 September, the San Miguel festival, a popular mass is held and a pilgrimage is done.