You know that, if you had a bent tube, one arm of which was the size of a pipe-stem, and the other big enough to hold the ocean, water would stand at the same height in one as in the other. Controversy equalizes fools and wise men the same way, — and the fools know it.

Oliver Wendell Holmes

Appian Way – Piranesi (1756)
A truly enormous version that shows its many, many details can be found at Wikipedia.

Gregorio Allegri – “Miserere mei, Deus”

No day like today to reflect on the enormities of mankind, the number and scope of which have, incredibly, survived centuries of prayer. The piece itself (I have learned) was forbidden to be performed outside the Vatican or transcribed, on pain of excommunication. It was only after a 14-year-old Mozart memorized it during attendance and copied it out from memory that it escaped the confines of the Sistine Chapel; the Pope himself praised Mozart and the music was released for general performance.