Impressed

Water Lilies, 1914 - 1926
 Each 6' 6 3/4" x 13' 11 1/4", 
Overall 6' 6 3/4" x 41' 10 3/8"

An artwork that I had been impressed by was Claude Monet's Water Lilies, because when I first saw it in person I was overwhelmed by the sheer size of the painting. I find that mere size of a work can make an artwork impressive, from the very tiny, with intricate detail and precision, to the very large, open with physical involvement and become lost in the wide view, and close up.

A quote from the MoMA website 

The aim of his large Water Lilies paintings, Monet said, was to supply "the illusion of an endless whole, of water without horizon or bank." ... his water-lily pond, and the sky above are the subjects of this monumental triptych, his representation of them can be seen to verge toward abstraction....In his enveloping, large-scale canvases Monet sought to create "the refuge of a peaceful meditation in the center of a flowering aquarium."

Other qualities that I think can make artwork impressive are there uniqueness, to be able create imagery and technique unique to the artist, and if the image can talk for itself, that the image can stand alone, with out explanations, or other pieces.