
According to dictionary.com a landmark can refer to "a significant or historic event, juncture, achievement, etc." Given that definition, then the New York Yankees winning their 27th World Series, defeating the Philadelphia Phillies would qualify as landmark status.
Another landmark status event would be today's ticker tape parade though the "Canyon Of Heroes." This is a New York City tradition that has been held roughly 200 times. A sampling of momentous occasions that this parade has been used to honor would include: 1886, a parade after the dedication of the Statue of Liberty, 1921, a parade for Albert Einstein, 1946, a 2 day parade event in celebration of the ending of World War II, and 1969, for Apollo 11.
Today: Names like Jeter, Sabathia, Matsui, and Girardi and the entire New York Yankees team were ingrained in tradition and history by being honored by this landmark parade. Following the parade they (the entire organization) were honored at a ceremony at City Hall and given the keys to New York City by Mayor Bloomberg forever welcoming them "home." Also, it is very sweet this year having a new landmark Yankee Stadium.
Of course none of this would have been possible if was not for the fan base who contributed to this landmark event. The fans passionately, and with undying loyalty, cheered their team on during the entire season. Today was no exception, the street was lined with thousands of people, 20 deep along the sides of Broadway, ecstatic for their hero's. People called off work and kids played hookie from school to come to watch the parade in person.
Here is to you Yankees, for being a landmark team with the greatest fans in the world!
Sources: CBS 2 and Wikipedia.