The Boston Marathon, first run in 1897, is the oldest big city marathon as well as one of the most prestigious. Everyone wants to run Boston, at least once, because of its history, the challenging course, and the the fact that you have to "qualify" to run it. Qualifying means running a certified marathon course in the year and a half (approximately) before the year you want to run Boston, within a certain time frame, which is determined by age. (Go here if you want more info on what you need to do to qualify for 2013. You will see that next year's qualifying times are more stringent than this year's... you will need to have run that qualifier five minutes faster.)
The course begins outside the city on Main Street in the town of Hopkinton and winds its way through Ashland, Framingham, Natick, and Wellesley, then up through the Newton Hills, then down to the city where it finishes in Copley Square near the John Hancock Tower. A note about the Newton Hills... there is a series of four moderately steep hills from about the 16-17 mile mark till about 20 miles, the last of which has been named "Heartbreak Hill," not because of any difficulty on getting over that last hill, but because of what happened during the race in 1936. It was on the last of the Newton hills where defending champion Johnny A. Kelley (you can read about MY Johnny Kelley story and photo posted here) caught and passed race leader "Tarzan" Brown, giving him a tap on the shoulder. That tap seemed to inspire Brown to surge ahead of Kelley and they fought for the lead briefly till Brown pulled ahead for good and went on for the win. A Boston Globe journalist reporting on the race used the term "heartbreak hill" describing how Johnny Kelley's heart was broken as he lost the race on that hill... and the name stuck.
Here is a brief "course tour" with Boston Marathon race director Dave McGillivray:
Last year I posted a video going through the course in 8 minutes. I'll post it again here: