Its origins date from 1543, the year in which Carlos V granted a Royal Certificate to finance the school.
For years, it catered to orphans of public servants but now the pupils are regular Madrid children including many immigrants.
CEIP[2] San Ildefonso participates in a bilingual program which was started in autumn of 2004 with British teaching assistants in 26 schools throughout Madrid.
Children, starting in first grade or primero de primaria, have at least a third of their classes in English (or a minimum of nine hours).
[3] For two centuries, children from CEIP San Ildefonso have sung the winning numbers of the Spanish National Lottery, including the hugely popular Christmas draw.