I believe NYC and Boston are the hardest. I've run both this year. I'd say NYC is a bit more difficult than Boston. I believe the 3 others are easier because they're flat.
I don't know which one is the hardest between London, Chicago and Berlin. I would think Berlin is the easiest, then Chicago then London followed by Boston and finally NYC.
Based on the assumption that the person asking is referring to a standard 26.2 mile marathon, and not an Ultra Marathon (50k and up). I would venture to say that Pikes Peak Marathon in Colorado is the toughest closely followed by the Equinox Marathon in Fairbanks Alaska. Others may disagree, but they probably haven't run the Equinox either... :)
The Snowdonia marathon is held each year around Snowdon. It is England and Wales' highest peak. The marathon is regarded the premier marathon held in the United Kingdom, and is also considered the most difficult to run.
Terrorism is difficult to define but it was most certainly a heinous act that should be condemned.
The five marathon "majors" are Boston, Berlin, Chicago, London and New York. Other, but by no means an exaustive list, marathons that have large participation include the Marine Corp Marathon, LA Marathon and the Paris Marathon.
World Marathon Majors was created in 2006.
The Marathon because it is long or the steeplechase because there are a few jumps (It has tripped people, believe me).
The oldest running annual marathon in the world
IAAF World Half Marathon Championships was created in 1992.
The top ten Marathons of the world are listed here: 1. London Marathon, April 2. Berlin Marathon, September 3. New York City Marathon, November 4. Chicago Marathon, October 5. Boston Marathon, April 6. Stockholm Marathon, June 7. Rotterdam Marathon, April 8. Paris Marathon, April 9. Honolulu Marathon, December 10. Amsterdam Marathon, October Hope it helped!
The first Boston Marathon, in 1897, was from Ashland to Boston.
London Marathon, with over 40.000 participants
Dubai Marathon$250K for the winner
Greece.