
The Panhandle Bridge, in the foreground, carries trolleys across the Monongahela River. Behind that, the Liberty Bridge; then the Tenth Street Bridge; and in the distance, the Birmingham Bridge. Below, a slightly different framing of the same view.

When Amtrak stopped using this bridge and the downtown tunnel into which it led, the Port Authority seized the opportunity. The bridge now carries the streetcars over the Mon and into the subway, the first part of which uses that old railroad tunnel—so that, like many other things in Pittsburgh, our subway is cobbled together from spare parts.
From Station Square across the river into the subway tunnel. You can also download a full-resolution version from the Wikimedia Commons file page.
“Night Scene on the Monongahela River Near Pittsburgh, Pa., Showing a Portion of the Plants of the Pittsburgh Steel Co.” A striking view from a booklet published by the Pittsburgh Steel Company in 1911.