Neoclassicism took inspiration from Ancient Greece and Ancient Rome Design. It spread throughout Europe and Western countries for nearly a century.

Image source: http://www.historywiz.com/exhibits/neoclassicalarch.html
Neo Classicism- Architecture
Neoclassical architecture is a revival of Classical architecture. The movement was interested with the logic of Classical volume with a tendency to reuse Classical features. Neoclassical architecture has the following characteristics:
- grandeur of scale
- simple geometrical forms
- Greek or Roman details
- dramatic use of columns
- blank walls.

Image source: https://commons.wikimedia.org/wiki/File:Montsec,_Meuse_(France),_Neoclassical_architecture_(9174508983).jpg
The Pantheon, in Paris was originally conceived as a monument to the French nation. It was the church of Paris’s patron saint. It can be considered Neoclassical because of these features:
- Classical forms, were fused with a Gothic type of design, including the use of concealed flying buttresses and relatively light stone vaultings.
- Greek cross in plan was used for the project and originally the walls were pierced with windows in each bay between the columns.

Image source: http://www.visual-arts-cork.com/history-of-art/neoclassical-architecture.htm
The Brandenburg Gate is an 18th-century neoclassical monument in Berlin, and one of the most famous landmarks of Germany. It was built on the site of a former city gate used to mark the start of a road from Berlin to the city of Brandenburg. The project was made by Carl Gotthard Langhans and the gate was finished between 1788 and 1791. It has twelve Doric columns, that form five passageways. On the top of the gate is a Quadriga, a chariot pulled by four horses by Johann Gottfried Schadow. The new gate was originally called the Peace Gate and the goddess is Eirene, that symbolises peace.
Info source: https://en.wikipedia.org/wiki/Brandenburg_Gate

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Neoclassic Interior design
Neoclassical furniture tends to be rectangular and does not use curves. It also features straight lines, with a logical order, and is influnced by Rococò furniture. Ornamentation is sometimes detailed and rich, always abundant. There is an important use of painting, light carving relief, and marquetry. Mahogany is the most used kind of wood, sometimes satinwood was also employed in this style.

Image source: http://www.furniturestyles.net/european/english/late-georgian.html
Info source: https://www.britannica.com/art/Neoclassical-architecture