Two blocks north of Vine Street, a fissure opens in the earth to reveal a subterranean realm that might be the remains of a lost civilization. Cathedral-like tunnels pierced by shafts of sunlight give way to a dense jungle. Occasional clearings occur, offering fish-eye views of towers looming above, a welcome reminder that Center City isn’t as far away as it seems.

Reading Railroad trains once roared through this urban canyon, ferrying coal to Philadelphia’s industrial belt. But since the last train made the trip in 1992 – delivering giant rolls of paper into the bowels of the former Inquirer/Daily News building – nature has been busy with its own landscaping. With modest structural improvements, advocates say, the industrial relic could be repurposed as an extension of the Reading Viaduct park, scheduled to complete construction drawings next year.

(Story continues: Changing Skyline: Tempting twin visions – Philly.com)