The Lecture Hall, part of the giant Carnegie Institute complex in Oakland. The graceful curve of this unexpected projection from the building is balanced by an equally graceful curve in the sidewalk.

The Cathedral of Learning, the fantastical Gothic skyscraper at the heart of the University of Pittsburgh, has recently been cleaned of all the soot and grime from the old days of big steel. The building is beautiful now, but the old grime had its own character and beauty. Here are a few pictures of the Cathedral of Learning before the cleaning.