Some reference information and statistics:
Marathon distance - 42 km 195 m
World record - 2 hours 3 minutes 59 seconds. It belongs to the Ethiopian Haile Gebrselassie and was set up at the Berlin Marathon in 2008.
According to the statistics if you are physically healthy, but have never run a distance more than 10 km, after a month of training by a special program you will be able to run a marathon distance for less than 6 hours, after 3 months - for less than 5 hours, after a half-year preparation - for less than 4 hours. Every week of training you will have to cover not less than 70 km.
To finish a marathon distance is equal to fulfilling a qualifying standard for the third sport class in the track and field athletics.
The New York City Marathon ranks first according to the number of simultaneously starting marathoners - 45 000 people.
On the average runners need not less than 3 months to allow the body to recover after the marathon or to reach a "pre-marathon" peak form, but there are individuals, who run a marathon distance once a week.
The most famous annual marathons (World Marathon Majors or Top 5) are London, Chicago, Boston, New York City and Berlin Marathons.
Among the most exotic places where marathons are officially held Ice Marathon in Antarctica and Sand Marathon over desert terrain in Sahara can be mentioned.

A dream of running one of the five World Majors has stuck in my mind since the time I ran ultra-long distances as training for Russian mountaineering championships. Of course all these special training programs, nutrition, diet and other peculiarities true marathoners are worried about were quite unusual to me.
A great role in the status of any competition, whether it is Marathon in Berlin or, for instance, gorodki-game in Urupinsk, plays its history. For comparison - Chicago Marathon has a more than 100-year history. But besides history the status is also influenced by participants and - we can't help mentioning it - prize money. Top 5 Marathons' budgets make up tens of millions of dollars, and among the participants are Olympic and world champions. The number of tourists who come from all over the world just to watch the event accounts for hundreds of thousands of people. Organizers of such high-level competitions have to think everything over in detail - from the number of portable WCs and attracted sponsors till choice of the city streets where the marathoners will run. It is not a secret that the routes are set through the most beautiful parts of the city - as millions of people will watch the TV-translation and the increase in tourist flow next year directly depends on its quality. In general any city would consider it an honour to hold competition of such scale, but it has established historically that London, Chicago, New-York, Berlin and London are the most successful herein.

It is not so simple to participate in these marathons, and the thing is even not in the start charge, every participant has to pay. Besides one should either have a confirmed high result (not more than 2 hours 50 minutes as a rule - in fact it is a qualifying standard for master of sports) or participate in a lottery, when the organizers ruffle places at the starting line roughly half a year before the competition. As a rule by the moment of drawing more than 500 000 (!!!) people are registered on the marathon website, whereas there are only 30 000 ruffled places.
Unfortunately I didn't have a chance to get ready for the start properly - I didn't have enough time for training, and a week before start I got back thigh muscle pull. Under these initial conditions a more or less acceptable result was out of the question - a minimum task was to toe the starting line, and the maximum one - to complete the distance. In fine I more starred at what was around me during the marathon than tried to outrun my "companions-in-arms". And there was much to look at - the New York City route goes through almost all its boroughs, and the whole population has gathered to watch the marathon. The start took place in Staten Island, then the 45 000 crowd ran to Brooklyn, then Bronx, Queens, Harlem, and the apotheosis was the finish in the Central Park in Manhattan. There were no records this year - I have run the distance for more than 5 hours, the winner - for 2 hours 9 minutes, but after finishing I didn't see any upset faces - one could see only supporters and participants smiling, and the atmosphere of a great holiday reigned everywhere.