After 5 years of restoration after the devastating fire that broke out in the gothic architecture symbol of Paris, its cathedral Notre Dame will reopen for the public next Sunday.

But behind the grandeur of the cathedral, which took 182 years to build between the 12th and 14th centuries, there are some amazing ones hidden stories. From medieval myths to modern mysteries, here they are five special things what you need to know about this Paris landmark:

The heart of France, literally

The importance of Notre Dame goes beyond its architecture and history. It is literally where all the roads in France begin.

In front of the cathedral, there is a simple bronze plaque and a stone with the inscription “point zéro des routes de France”, which means “starting point of the roads of France”. This plate marks the starting point for measuring distances between Paris and the other cities across the country.

While the plaque was installed in 1924, the idea for a “zero point” dates back to 1769. King Louis XV envisioned a reference point for France’s growing road network, an idea that tied the nation’s geography to the heart of Paris.

The great myth of the gargoyles

These terrifying stone creatures at Notre Dame may look ancient, but all is not what it seems. The actual gargoyles, which are monster-shaped gutters used to drain rainwater, have been around since the time the cathedral was built. But the dramatic monster-like figures often depicted in postcards and movies are chimeras.

In the 19th century, the architect Eugène Viollet-le-Duc, who was responsible for renovating the then decaying building, added these creatures to add a sense of mystery to the cathedral. Viollet-le-Duc drew inspiration from Victor Hugo’s famous book ‘The Hunchback of Notre Dame’ to create these demonic animal figures with personified expressions.

How to tell them apart? The gargoyles look like horizontal spikes that protrude from the facade and have holes in their spouts that allow water to drain.

A revolutionary makeover

During the French Revolution, which saw waves of protest against the Church, Notre Dame wasn’t exactly treated with the respect a cathedral deserves. In 1793, the revolutionaries removed her from their religious symbols and renamed her “Notre-Dame de la Raison” (Our Lady of Reason).

Instead, the cathedral hosted festivals celebrating the ideas of science and the Enlightenment, and for a short time was even used as a wine cellar.

Religious services resumed in 1795 and Notre Dame regained its sacred status at the urging of French Emperor Napoleon I, who had his coronation there in 1804, immortalized in a famous painting by Jacques-Louis David.

The beheaded kings returned

In 1792, revolutionaries also decapitated 28 statues from the facade of Notre Dame, mistaking them for French monarchs. They were actually ancient kings of Judah, biblical ancestors of Jesus. Their heads were considered lost forever, possibly destroyed or sold as building materials.

But in 1977, workers renovating a courtyard in the 9th arrondissement of Paris discovered hundreds of fragments of stone sculptures. Experts confirmed that they were the lost heads of the Kings of Notre Dame. How they ended up being buried there remains a mystery.

Today, 22 of the heads have been restored and are on display at the Cluny Museum in Paris. Their discovery is considered one of the most remarkable archaeological finds in the modern history of the city.

A wake-up call about lead dust

The 2019 fire that nearly destroyed Notre-Dame de Paris revealed the serious health risk. When the flames melted the roof, tons of toxic lead dust was released into the air and settled across Paris.

Then, authorities discovered that there were no rules for measuring the risk of outdoor lead dust. But this was not just a Paris issue. Major cities like London and Rome, and even the World Health Organization, have no guidelines for outdoor lead pollution.

The fire at Notre Dame highlighted a hidden problem, forcing officials to take a closer look at their safety standards.