Where was the Constitutional monarchy?

Answer 1

Constitutional monarchy was not invented, it was developed.

In Britain, the Glorious Revolution of 1688 led to a constitutional monarchy restricted by laws such as the Bill of Rights 1689 and the Act of Settlement 1701, although limits on the power of the monarch ('A Limited Monarchy') are much older than that going back to Magna Carta.

Poland established a constitutional monarchy on 3 May 1791, it was the second written constitution on the world after United States, the first in Europe and the first written constitution regulating a monarchy. However, because of the Partitions of Poland, the government it established lasted less than 10 years, after which the Third Partition returned all of Poland to non-constitutional monarchy.

General Napoleon Bonaparte is considered the first monarch proclaiming himself as embodiment of the nation (1804), rather than as a divinely-appointed ruler; this interpretation of monarchy is basic to continental constitutional monarchies.