The monastery of San Millán de Suso or Suso monastery is located near the town of San Millán de la Cogolla, on the left bank of the Cárdenas River.

It is part of the monumental complex of two monasteries, together with another built later and located further down, called the Monastery of San Millán de Yuso, both declared World Heritage Sites.

Its construction started at the end of the 6th century, it has its origin in a Visigothic monastery established around the tomb of the hermit Aemilianus (Millán) or Emiliano, who died in 574.

Throughout the following centuries and until the 12th century it underwent different extensions as a consequence of the change of hermitic life to the cenobitic and later monastic, distinguishing in them the Mozarabic and Romanesque style.

Its importance is not only artistic and religious, but also linguistic and literary. Here a monk wrote the Emilian Glosses, which were explanatory annotations in the margins of the pages written in Latin. These notations were written in romance.

In this monastery the first annotations written in Euskera appear, for which reason it has been considered the cradle of said Hispanic romances and Euskera.

The monk and the first poet with a known name in Spanish, Gonzalo de Berceo, also lived here.

Also the tradition attributes that in the "portaliello" of this monastery are those that happen to be the sarcophagi of the seven infants of Lara of the legend.

In the early days of the arrival of the Visigoths to the Peninsula, the anchorite Aemilianus (Millán), son of a shepherd and a native of Vergegium, now Berceo, retired to this remote and remote place. Here he lived as a hermit, sheltered in a small cell, dying at the age of 101 and being buried in a rock-cut tomb.

The small monastery was built around the hermit's rock cell. In the first stage (5th century and early 6th century) caves are excavated taking advantage of cavities in the ground, which are distributed in two levels for rooms, and another two for oratory, where currently the cenotaph of San Millán and the ossuary are located.