Riding the subway might feel like a quick ... studied air quality at the 15th Street-City Hall station, one of the busiest stops on Philadelphia's Market-Frankford and Broad Street Lines.

More information: Anjum Shahina Karim et al, Assessment of air quality in the Philadelphia, Pennsylvania subway, Journal of Exposure Science & Environmental Epidemiology (2024). DOI: 10.1038 ...

City Hall Station and Walnut-Locust Station subway stations. The busiest part of Philadelphia is downtown or Center City, where the old and the modern come together. The neighborhood is ...

Learn about the history, architecture, design, and engineering hidden underneath your feet on these urban transit system tours.