Hidden City Philadelphia, a brand under CultureTrust, is dedicated to exploring and uncovering the rich tapestry of Philadelphia's urban landscape. Through their online publication, the Hidden City Daily, they serve as a watchdog for historic preservation in the city, while also delving into topics such as architecture, urbanism, photography, public art, city life, and Philly history. Their mission is to surprise, delight, and inform readers by showcasing the often neglected post-colonial history of Philadelphia.

Hidden City Tours offer a unique way for locals to view familiar places with fresh eyes, offering exclusive visits to extraordinary sites like the vacant Red Bell Brewery, as well as walking tours highlighting locations such as Mt. Moriah Cemetery, the Lost Jewish Quarter, and Subterranean Philadelphia. Hidden City Philadelphia originated from founder Thaddeus Squire's passion for exploring old estates, churches, and factories, which led to the creation of the Hidden City Festival in 2009.

This festival featured site-specific contemporary art and performances in obscure or abandoned places. Today, as a non-profit organization, Hidden City continues to connect local residents to Philadelphia's vibrant history. They have received multiple awards and critical support from various organizations, including the Pennsylvania State Historic Preservation Office and the Vernacular Architecture Forum