Workers finishing New York's tallest building at the World Trade Center are leaving their personal marks on the concrete and steel: graffiti.

The scribbles appear on beams, walls and stairwells of the skyscraper that's rising to replace the terror-wrecked towers.

They range from tributes to 9/11 victims to off-color sketches and poetry.

The words "Change is from within" are scrawled on an iron beam in the 104-story high rise that soars above the trade center site.

One of the last beams for One World Trade Center hoisted up last year has a special handwritten message: "We remember. We rebuild. We come back stronger!" It's signed "Barack Obama."

Ironworker Kevin Murphy says the graffiti is a way for workers to get their feelings out following 9/11.