The classicism that flourished in the period 1750-1830 is often known as Neoclassicism, in order to distinguish it, perhaps unnecessarily, from the classical architecture of ancient Rome or of the Renaissance. In the 18th century, modern classicism was described as the "true style," the word Neoclassical being then unknown. The search for intellectual and architectural truth characterized the period. Stylistically this began with an onslaught on Baroque architecture, which--with its emphasis on illusion and applied ornament--was felt to be manifestly untruthful. As early as the 1680s the French architect Claude Perrault had undermined the Renaissance concept of the absolute right of the orders. According to Perrault, the proportions of the orders had no basis in absolute truth but were the result of fancy and association. The consequent attempt to discover a new basis for architectural reality took many forms, from archaeology to theory.

Essentially representing a new taste for classical serenity and archaeologically correct forms, 18th-century classicism manifested itself in all the arts. It corresponded to a new attitude toward the past that began to be perceptible about 1750. In Europe it represented a reaction against the last phase of the Baroque and was symptomatic of a new philosophical outlook. As the Baroque was the style of absolutism, so Neoclassicism corresponded loosely with the Enlightenment and the Age of Reason. Coincidental with the rise of Neoclassicism and exerting a formative and profound influence on the movement at all stages was a new and more scientific interest in classical antiquity. The discovery, exploration, and archaeological investigation of classical sites in Italy, Greece, and Asia Minor were crucial to the emergence of Neoclassicism.

Neoclassicism, in its nostalgia for past civilizations and its attempt to re-create order and reason through the adoption of classical forms, was, paradoxically, also a Romantic movement. Prompted by feeling as well as by reason, architects interested themselves as much in the picturesque aspects of nature and objects in nature (such as ruins) as in rational procedures. While superficially opposite, Neoclassicism and Romanticism share the same roots. Two movements as different as the Greek Revival and the Gothic Revival were essentially alike, sharing, at least in their earlier phases, similar motivations and even compositional expressions and equally reflecting the mood of the age that created them. The term Romantic Classicism has been used by some 20th-century art historians to describe certain aspects of Neoclassical architecture. This widening of the term admits non-Greco-Roman forms and the many attempts to imitate Chinese, Moorish, Indian, Egyptian, and, of course, Gothic buildings.

The emergence of the science of archaeology was indicative of a new attitude to the past in which separate and distinct chronological periods could be distinguished. This sense of a plurality of valid styles replaced the older conception of classical Rome as the unique object of veneration. An important architectural corollary of this idea, which was to spring into prominence in the 19th century, was the notion of a modern style of building. Just as the past could now be interpreted and re-created by the study of a diverse range of monuments, each now seeming to be uniquely characteristic of its own particular moment in time, so it was thought possible that a mode of building reflecting the present, a mode recognizable by future archaeologists as uniquely representative of their own time, might be created.