ST. LOUIS, Mo. (NewsNation Now) — On the 19th anniversary of the 9/11 terror attacks, one of the most powerful tributes to the victims remains an emotional ad featuring the Budweiser Clydesdales — and it has aired only once.

The rare ad aired during Super Bowl XXXVI on Feb. 3, 2002. In the ad, horses honor the memory of the fallen victims with an graceful bow.

Anheuser-Busch’s creative team came up with the concept and had to get approval from members of Congress, the advertising community and from New York Mayor Rudy Guiliani to make the commercial.

“We filmed in New York City,” Bob Lachky, former executive vice president of Anheuser-Busch Global Creative, told NewsNation affiliate KTVI. “We had a helicopter going over the Brooklyn Bridge. Mayor Giuliani let us into the city — the only film company of any sort right after 9-11. To actually come into air space with our helicopter to film the Clydesdale … the hitch coming into Battery Park and it was amazing, just amazing.”

The company’s logo is absent throughout the entire video until the very end.

Though the original ad has only aired one time, Budweiser aired an updated version of the commercial on Sept. 11, 2011, the 10th anniversary of the attacks.

NewsNation affiliate KTVI contributed to this report.