I actually took this photo a while ago, but it has such strong lines, movement, variation and contrast that I just had to include it. The rainbow is striking and is an excellent line. Also, I love the power lines intersecting each other and the rainbow.
I like the use of lines in this photo because they're not in-your-face blunt; you kind of have to look for them. The first line of the curb grabs your eye and leads it to the line of the bridge. The bridge seems to bring the viewers eye back around to then notice the lines of the trees and the lamp posts.
There is so much repetition and variation in this photo. First I noticed the lines in the brick pattern and the lamp posts on the sidewalk. the long consistent line down the road adds some balance and stability. The repetition is also used again in the windows on the building to the right.
This picture is my favorite because of the symmetry. The curves in the descending lawn brings the viewers eye to the focal point of the fountain and the arcs of water. the vertical lines of the trees and the various lines that make up the bridge in the background bring even more movement and variation.
This photo is composed of almost all lines. the intersecting lines on the outside of the building and the ones on the inside of the building show a lot of variation and repetition. The trees at the bottom add an interesting and different kind of line.