Classical Architecture

Classical architecture is a mode of architecture employing vocabulary derived in part from the Greek and Roman architecture of classical antiquity, enriched by classicizing architectural practice in Europe since the Renaissance. Classical architecture has inspired many more recent architects and has led to revivals such as neoclassical architecture from the mid-18th century and the Greek Revival of the 19th century.(www.wikipedia.org)
Some elements can still be found in today's architecture. For example, the stone domes of our nation's capitol is a great example of the Classic Architecture's rendition of a domed building complex. Also, the brackets as well as the arches have the same basic idea. The architects of that time made every building symmetrical down to the smallest component.
A well known example of Classical Architecture is the  Greek Parthenon. (shown below)

(rozanehmagazine.com)
I am Irish and found a website describing architecture of the Classical period in Ireland. The first Classical public building was the Royal Hospital in Dublin. Designed by Sir William Robinson and built in 1680-84, it was a home for retired soldiers modelled on Les Invalides in Paris. The buildings are ranged around an arcaded courtyard, with the great hall and chapel on one side and the living quarters on the other three. The building is now completely restored. (http://www.ireland-information.com/reference/classic.html)


This is the Royal Hospital. (irelandposters.com)