The Graffiti Pier, dubbed by one blogger as Philadelphia's secret museum of street art, is situated along the Delaware River north of Philadelphia's Sugar House Casino. This unique feature was originally built as a coal pier. The elevated concrete structure brought rail cars filled with anthracite coal to barges along the river, where they were emptied of their contents and sent along their way to be refilled. Conrail closed the site in 1991 when they moved their coal operations to Baltimore, and has left the site to go to ruin ever since. Secluded and guarded by an obligatory 'No Trespassing' sign, the site is a fascinating study in street art. Vestiges of some of the more famous local artists can still be seen along its walls and arches.