From PGFD:

The 2015 Prince George’s County Memorial Stair Climb and Walk is a way to honor and remember the FDNY firefighters who selflessly gave their lives so that others might live on 9-11-2001. Each participant pays tribute to an FDNY firefighter by climbing or walking the equivalent of the 110 stories of the World Trade Center. Your individual tribute not only remembers the sacrifice of an FDNY brother, but symbolically completes their heroic journey to save others. Through firefighter and community participation we can ensure that each of the 343 firefighters is honored and that the world knows that we will never forget.

For more details, go here: http://events.firehero.org/site/TR?fr_id=1240&pg=entry