Arguably the most famous marching band routine in the U.S. and performed at virtually every Ohio State University college football game by The Ohio State University Marching Band (a.k.a. The Best Damn Band in the Land or TBDBITL for short).
The routine was designed in 1936 by then director Eugene Weigel. The band starts by forming a block of three concentric rectangles in the middle of the
field while playing the OSU fight song "Across The Field". While the block is forming, the drum major marches to the lower left corner of the block.
After finishing "Across The Field", the band starts to play the march "Le Regiment de Sambre et Meuse" by Jean Robert Planquette and P. Raulski. The band has used various arrangements over the years. The current arrangement was done in 1964 by Richard Heine.
As "Le Regiment" starts, the drum major starts to march toward the sideline. The band members at that corner start to follow him in a single file line, with 2 steps (45 inches) seperating each band member from the next. (The standard marching step size is 22-1/2 inches, giving 8 steps in 5 yards.) Essentially, the drum major is the pen, writing the word "Ohio" on the field in script, and the band members are the ink.
Meanwhile, the block is unwinding. The outside rectangle of the block rotates counterclockwise, the middle rectangle rotates clockwise, and the inner rectangle rotates counterclockwise, the same as the outside rectangle. The differing rotation directions produce an interesting flashing visual effect, because you can see the green field through the spaces when the band members are lined up, but the green disappears behind the band members' black uniforms when they are not. This change of direction also means that the members have to make a quick U-turn (2 90 degree turns 2 steps apart) inside the block.
Another difficulty for the band members is the crossover. The script design has two crossovers in it. Remember that 45 inches between band members? That spacing still holds when you reach the crossover. You have to squeeze yourself through the gap, and not hesitate so you don't get run over by the next person coming the other way. An unlucky band member might have to go through 4 crossovers (2 crossovers, 2 directions).
Finally, the pièce de résistance. One sousaphone player (a 4th year band member) has made his way through the script and stands poised, along with the drum major, at the top left corner of the second "o". The drum major then leans back, kicks his legs straight out in front of him, and prances to the dot at the top of the "I". The sousaphone player then follows suit. The sousaphone player gets to the top of the "I" and then does an elaborate "Hats Off!" bow and salute to the crowd, as "Le Regiment" ends. This is known as "Dotting the I" and is the highlight of the sousaphone player's band career.
The finished formation looks something like this (please pardon the BUAG)
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Sources:
http://www.acs.ohio-state.edu/org/osuband/music/songs/lereg.html
http://www.osu.edu/org/osuband/history/index.html