Boston Citgo sign, Commercial neon sign in Kenmore Square, Boston, US.

The Boston Citgo sign is a large commercial advertisement with a red triangular logo on a white square located in Kenmore Square. Its LED lights are visible from many parts of the city and make it a recognizable feature of the local skyline.

The sign was installed in 1940 as an advertisement for Cities Service and was redesigned into the current Citgo logo in 1965. The structure later underwent an upgrade to LED lighting in 2005 to replace its original neon system.

The sign appears in broadcasts of Boston Red Sox games and during the Boston Marathon, where it serves as a recognizable landmark for many residents and visitors. People have come to view it as a defining part of their city's identity.

The sign is easily visible from Kenmore Square and can be spotted from several vantage points around the city. The best views are obtained by approaching the square directly or standing on nearby streets with clear sightlines.

In 1983, after Citgo tried to dismantle the weather-beaten sign, a campaign led by preservationist Arthur J. Krim saved it; the relighting drew a cheering crowd of 1,000. The sign has no gas station beneath it, only a former Cities Service station on the ground floor.