During the 13th Century, Paris was in the forefront of trade and political power and boasted prestigious innovative early-Gothic architecture. The great span and scale of Notre Dame’s vaults surpassed all previous architectural accomplishments. The cathedral’s subtle transverse arches and triangular ribs allowed its interior to be viewed without interruption of supporting elements. Notre Dame was one of the first of religious buildings in the world to incorporate the early Romanesque ‘flying buttress' architecture.

Notre Dame has undergone a series of renovations, some of which resulted from acts of vandalism. In the end of the 17th Century, during the reign of Louis XIV and Louis XV, the cathedral experienced major modifications. During the French Revolution of 1793, many of the treasures kept in the cathedral were destroyed or stolen, including some of its stain glass, the spire and sculptures. However, the 1845 restorations by architects Viollet-le-Duc and Jean-Baptiste-Antoine Lassus replicated much of the stain glass, sculptures and the cathedral's fleche, or the timber spire, on its roof.

The apse, choir and chancel of the cathedral were the first to be completed so that religious services could take place despite the ongoing construction. Notre Dame's 400-stair, 68-m high towers, finished much later, allow you to see the cathedral’s beautiful spire, the Île de la Cité and all of Paris. The south tower is where the cathedral’s famous thirteen-ton bell hangs.

Notre Dame's plaza, designed in the 19th Century, provides a fantastic view of the façade’s three, 13th-century decorative portals. The left Portal of the Virgin represents the life of Virgin Mary, as well as an astrological calendar and a coronation scene. The first and second panels of the central portal represent the Last Judgment, including the resurrection of the dead, Christ and the apostles. The Portal of Saint-Anne highlights Notre Dame's oldest, 12th-century sculpture of the Virgin Mary sitting on a throne, with the baby Jesus in her arms.

The interior of Notre Dame is equally impressive, not only because of its modern stained glass but rather the three, much older stained-glass rose windows. The most impressive north window, dating back to the 13th Century, displays figures surrounding the Virgin Mary, while the south window depicts the Christ surrounded by angels and saints.