The recognition of The Decreta of León of 1188 as the “oldest documentary manifestation of the European parliamentary system” by UNESCO on 19 June 2013 and its inclusion in the International Memory of the World Register is the starting point of this paper. The article is based on the following dialectic methodology. Thesis: England first developed the idea of representative government and parliamentary institutions. Antithesis: the Decreta of Leon 1188 predates any historical reference to parliamentary representation. Synthesis: citizen attendance, the procedure and the content of the Decreta of Leon 1188, supported by the UNESCO recognition proves that Leon is the “cradle of parliamentarism”. This historical review seeks to stimulate reflection about the present situation of parliamentary democracy and, in particular, the crisis it is undergoing. The need of citizen re-engagement with political processes , especially via the involvement of constitutional conventions in the amendment of constitutions should be our point of reference. What are the main lessons from history for today?