The idea of a national constitution for Spain arose from the Declaration of the Rights of Man and of the Citizen initiated as a result of the French Revolution.
A major feature of the Constitution of 1808 was the provision for representation by Spanish America on an equal basis with the peninsula.
During Francoist Spain, there were many attempts to create stable institutions that did not (at least directly) emanate from Francisco Franco as they did in the post-war period.
The Fundamental Laws of the Realm (Spanish: Leyes Fundamentales del Reino) were a constitution in parts enacted through nearly 20 years starting in the 1950s.
They established the very institutions that would later, under Juan Carlos I and Prime Minister Adolfo Suárez, commit "constitutional suicide" and pass the Political Reform Act, starting the Spanish transition to democracy.