Luminous X sign glows on roof of Twitter building in San Francisco

A giant X sign has been installed on top of the Twitter building in San Francisco.

The huge luminous letter was placed on the headquarters on Friday, 28 July, amid owner Elon Musk’s continued rebrand of the social media platform.

San Francisco officials have launched an investigation into the X sign, as city officials say replacing letters or symbols on buildings, or putting a sign on top of one, requires a permit.

According to the city’s Department of Building Inspection, a permit is needed to ensure “consistency with the historic nature of the building” and safety protocols are followed.