Helsinki City Marathon - August. The Helsinki City Marathon has a worldwide reputation of being a tough and fast competitive run through an unusually scenic and next-to-nature Nordic city landscape. Along this course you will see an overwhelming amount of glittering water and breath refreshingly clean sea air. The start of the marathon is close to the Helsinki Olympic Stadium originally built for the 1952 Olympic Games. From there the route continues to the colorful Marketplace in South Harbor by covering miles of beautiful waterfront, many bridges and islands on which the city of Helsinki is built. The finish line is at the Olympic Stadium.