Though it may sound weird, history shows that the Notre Dame cathedral now stands at the place where there was once a Gallo-Roman city by the name of Lutetia. When the excavation was carried out in 1710, some pieces of sculpted alter belonging to Jupiter was discovered right below the cathedral pointing to the fact that there may have been a temple earlier to it. Some other architectural ruins from the same era were also found out during the 1960s and 70s. These are preserved in the archeological crypt that is located below the square just opposite to Notre Dame.
The iconic roof of Notre Dame that has partially burnt down in the ravaging fire was made up of some oldest surviving timber frames. During the 12th-century, about 52-acres of trees were cut to build the structure. Each beam of the structure was designed from a particular tree! It is also a reason why its woodwork lattice was commonly referred to as "the Forest".
During the French Revolution in 1793, 28 statues of erstwhile kings kept here were taken down and beheaded by the people. The mangled heap of stones was ordered by the Minister of the Interior to be used for some other construction purpose. In 1977, while working on the basement of the French Bank of Foreign Trade, 21 heads out of 28 were discovered by workers. They have since been kept for viewing by people at the Musee de Cluny that is located very close to the cathedral.
The heads of the statues of 28 kings were not the only ones to have been taken down from the cathedral. During the late 18th-century, the cathedral was converted from a Christian space into the new Cult of Reason. As such, all its 20 bells excluding the giant 1681 bourdon known as Emmanuel - were taken down and melted for making cannons!
However, during the 19th-century, these bells were replaced but the sound of them was not the same as earlier. Ultimately, in 2013, a new set of bells were finally made that resonated with the sound of the earlier 17th-century.
At a glance, the towers of the cathedral may seem to be like twins but on closer inspection, one can easily find out that the north tower is slightly bigger in size than the southern one. The cathedral was not designed by any one person. Rather, it was built gradually over a period of time and reflects the leadership and architectural trends of that period. It is more of a collection of thoughts that leaders displayed at the time.
The gargoyles or the monsters of Notre Dame are very special as they have been depicted in many places throughout the world when the cathedral is mentioned. However, it can be interesting to know that these creatures were not there till the 19th-century. Between 1843 and 1864 when the cathedral was being restored by the architect, Eugène-Emmanuel Viollet-le-Duc, these were added during that time.
When Victor Hugo wrote "The Hunchback of Notre Dame", le-Duc was greatly moved by the account and the creatures may have captured his imagination at that time. However, many of these gargoyles are just deteriorating as of date due to want of proper maintenance.
These are only some of the most interesting facts regarding the cathedral that may not be there much in the public domain. The cathedral has not only been a witness to rich history but has also been a standing ovation to the French culture that has revolved around it and that's what makes it so special for the city.