This holiday is always celebrated annually on 3 May.
In Polish, it is known as 'Swieto Trzeciego Maja', which means 'National Third of May day'.
Constitution day marks the declaration and adoption of Poland's first constitution on 3 May 1791.
This was the first constitution to be adopted in Europe and second only in the world - the American constitution of 1789, being the oldest. The first draft of the Polish constitution dates back to 1788.
The Polish constitution was based on principles influenced by the French revolution and introduced a constitutional monarchy.
The constitution itself applied to the Polish-Lithuanian commonwealth and the implementation of the constitution led to the 'War of the defense of the constitution' between the commonwealth and conservative nobility backed by the Russia empire.
This led to the annulment of the constitution just 19 months later, but the 3 May constitution is still regarded as a key event in the history of Poland.
After gaining independence in 1918, this day became a holiday, but like many national holidays it was not celebrated during the the time of the Soviet empire.
Following the collapse of the Soviet Union, the holiday was restored by the Act of 6 April 1990 and the first gala celebration took place in Warsaw's Castle Square on 3 May 1990 in the presence of President Wojciech Jaruzelski.