The name Marathon comes from the legend of Philippides or Pheidippides, the Greek messenger. The legend states that he was sent from the battlefield of Marathon to Athens to announce that the Persians had been defeated in the Battle of Marathon (in which he had just fought),which took place in August or September, 490 BC. It is said that he ran the entire distance without stopping and burst into the assembly, exclaiming νενικήκαμεν (nenikēkamen, "we have won!"), before collapsing and dying. :)
The origin of the name of Istanbul belongs to the Greek phrase “in the city”. People both in the city and in the surrounding region referred to anything within its old walls as "εις την Πόλιν" (eis tin polin) or simply "in the city" and this phrase became "Istanbul" in Armenian and later in Turkish.