The truly Romanesque phase actually began late, around the 13th century. A document during the reign of King Afonso II of Portugal mentioned the construction of the building during the reign of Afonso I of Portugal, although archaeological proof of these statements have yet to be discovered on the site.
The true start of the Romanesque era was around the 13th century, as documented in a Portuguese royal decree during the reign of Afonso II.  However, despite this historical record, no archaeological evidence has been found at the construction site to support these claims.