The Louis XIV style or Louis Quatorze (/ˌluːi kæˈtɔːrz, - kəˈ-/ LOO-ee ka-TORZ, -⁠ kə-, French: [lwi katɔʁz] ^ⓘ), also called French classicism, was the style of architecture and decorative arts intended to glorify King Louis XIV and his reign. It featured majesty, harmony and regularity. It became the official style during the reign of Louis XIV (1643–1715), imposed upon artists by the newly established Académie royale de peinture et de sculpture (Royal Academy of Painting and Sculpture) and the Académie royale d'architecture (Royal Academy of Architecture). It had an important influence upon the architecture of other European monarchs, from Frederick the Great of Prussia to Peter the Great of Russia. Major architects of the period included François Mansart, Jules Hardouin-Mansart, Robert de Cotte, Pierre Le Muet, Claude Perrault, and Louis Le Vau. Major monuments included the Palace of Versailles, the Grand Trianon at Versailles, and the Church of Les Invalides (1675–1691).

The Louis XIV style had three periods. During the first period, which coincided with the youth of the King (1643–1660) and the regency of Anne of Austria, architecture and art were strongly influenced by the earlier style of Louis XIII and by the Baroque style imported from Italy. The early period saw the beginning of French classicism, particularly in the early works of Francois Mansart, such as the Chateau de Maisons (1630–1651). During the second period (1660–1690), under the personal rule of the King, the style of architecture and decoration became more classical, triumphant and ostentatious, expressed in the building of the Palace of Versailles, first by Louis Le Vau and then Jules Hardouin-Mansart. Until 1680, furniture was massive, decorated with a profusion of sculpture and gilding. In the later period, thanks to the development of the craft of marquetry, the furniture was decorated with different colors and different woods. The most prominent creator of furniture in the later period was André Charles Boulle. The final period of Louis XIV style, from about 1690 to 1715, is called the period of transition; it was influenced by Hardouin-Mansart and by the King's designer of fetes and ceremonies, Jean Bérain the Elder. The new style was lighter in form, and featured greater fantasy and freedom of line, thanks in part to the use of wrought iron decoration, and greater use of arabesque, grotesque and coquille designs, which continued into the Louis XV style.

The model of civil architecture in the early part of the reign was Vaux le Vicomte (1658), by Louis Le Vau, built for the King's Superintendent of Finances Nicolas Fouquet and completed in 1658. Louis XIV charged Fouquet with theft, put him prison, and took the building for himself. The design was strongly influenced by the classicism of François Mansart. It combined a façade dominated and rhymed by colossal classical columns, beneath a dome, imported from the Italian Baroque architecture, along with a number of original features, such as a semicircular salon which looked out on the vast French formal garden created by André Le Nôtre.

Based on the success of Vaux le Vicomte, Louis XIV selected Le Vau to construct an immense new palace at Versailles, to augment a smaller palace transformed from a hunting lodge by Louis XIII. This gradually became, over the decades, the master work of the Louis XIV style. Following the death of Le Vau in 1680, Jules Hardouin-Mansart took over the Versailles project; he broke away from the picturesque projections and dome and made a more sober and uniform façade of columns, with a flat roof topped by a balustrade and row of columns (1681). He used the same style to harmonize the other new buildings he created at Versailles, including the Orangerie and the Stables. Hardouin-Mansart constructed the Grand Trianon (completed 1687), single-story royal retreat with arched windows alternating with pairs of columns, and a flat roof and balustrade.

Another major new project undertaken by Louis was the construction of a new façade for the east side of the Louvre. In 1665 Louis invited the most famous sculptor architect of the Italian Baroque, Gian Lorenzo Bernini, to submit a design, but in 1667 rejected it in favor of a more sober and classical colonnade, designed by a committee of three, comprising Louis Le Vau, Charles Le Brun, and Claude Perrault.

In the early period of his reign, Louis began building the church of Val-de-Grâce (1645–1710), the chapel of the Val-de-Grâce hospital. The design was worked on successively by Jules Hardouin-Mansart, Jacques Lemercier and Pierre Le Muet before being completed by Gabriel Leduc. Its picturesque tripartite façade, peristyle, detached columns, statues, and tondi, make it the most Italianate and Baroque of Paris churches. It served as the prototype for the later domes of Les Invalides and the Panthéon.

The next major church built under Louis XIV was the church of Les Invalides (1680–1706). The nave of the church, by Libéral Bruant, was comparable to those of other churches of the period, with ionic pilasters and penetrating vaults, and an interior that resembled the high baroque style. The dome, by Hardouin-Mansart, was more revolutionary, sitting upon a structure with the plan of a Greek Cross. The design used superimposed orders of columns, in the classical style, but the dome achieved greater height, by resting on a double tambour or drum, and the façade and dome itself were richly decorated with sculptures, entablements in niches, and ornaments of gilded bronze alternating with the nervures, or ribs of the dome.

The finest church interior of the late Louis XIV period is the chapel of the Palace of Versailles, created between 1697 and 1710 by Hardouin-Mansart and his successor as court architect, Robert de Cotte. The decor was carefully restrained, with light colors and sculptural detail in slight relief on the columns. The interior of the chapel opened up and lightened by the use of classical columns placed on the tribune, one level above the ground floor, to support the weight of the vaulted ceiling.