Notre Dame is one of the most famous monuments in the world, attracting 12 million visitors per year.
She's considered a masterpiece of Gothic architecture - and is protected as a world heritage site.
Her construction began in the 12th century and took 200 years to complete.
In the 12th century, medieval Paris was growing in size and importance.
A new and ambitious bishop, Maurice de Sully, wanted to build a cathedral to host his rapidly growing congregation and compete with other influential cities and abbeys.
He chose the flamboyant Gothic style - a new architectural style recently tested at the royal abbey of Saint-Denis, just outside of Paris.
It's hard to overstate how impressive Notre Dame would have been at the time.
She was the largest religious building in the Western world - measuring a massive 120 x 40 x 70m.
She towered above Parisian buildings - and remained the highest building in Paris until the construction of the Eiffel Tower in 1889!