Dam Square is not only the most important but also the most well-known square in Amsterdam. It lies in the historical center of the city and boasts structures such as the Royal Palace, the Nieuwe Kerk (New Church), the National Monument Pillar and the Madame Tussaud's Wax Museum. It lies 750 meters south of the Central Station, the main railway station in Amsterdam and very close to the main red-light district: de Wallen.
My friend and I walked there with our bicycles - it was a Saturday evening and too crowded to bike! Nevertheless, we had a good time wandering about the Square, and I was almost run over by a flock of pigeons, who seemed to be waiting in ambush for me! Check out the pictures!
Also, read my post on 10 things to do in Amsterdam.