What do classical music and neoclassical architecture have in common?

Both have in common an aesthetically distinct, harmonious, objective and rigorous structure, absent from informality, excessive emotions and coming from the human soul.

a period of artistic style that used exaggerated motion and clear, easily interpreted detail to produce drama, tension, exuberance, and grandeur in sculpture, painting, architecture, literature, dance, and music. The style began around 1600 in Rome, Italy and spread to most of Europe. Much like Classical music. melodie are among the most tuneful and easy to remember. The themes of even highly sophisticated compositions may have a folk or popular flavour. Occasionally, composer simply borrowed popular tunes, but more often, they wrote original themes with a popular character. melodies often sound balanced and symmetrical because they are frequently made up of two phrases of the same length. The second phrase, in such melodies, may begin like the first, but it will end more conclusively and it will be easier to sing.