In what way is the round arch an improvement over the post and lintel?

The round arch improved on the post and lintel system that the Greeks used. the post and lintel limited the space builders could bridge . a stone lintel could not be used to span a wide space because it would break . unlike a lintel , an arch is made of a number of bricks or cut.

i believe the correct answer is: must sculpture be beautiful to be considered art?

the aesthetics represents the exploring of beauty and taste of nature in art, with the creation and appreciation of beauty. having that in mind, i believe the appropriate aesthetic question you could ask about gianlorenzo bernini’s sculpture david is “must sculpture be beautiful to be considered art? ”.