Heights. Columbia University has an extensive tunnel system, more than a century old, with the oldest portions predating the present campus. Some of these remain accessible to the public, while others have been cordoned off.
Butler Library is the largest in the Columbia University Libraries system and one of the largest buildings on the campus. It was completed in 1934 and renamed to Butler Library in 1946. As of 2020, Columbia's library system includes over 15.0 million volumes, making it the eighth largest library system and fifth largest collegiate library system in the United States.
Several buildings on the Morningside Heights campus are listed on the National Register of Historic Places. Low Memorial Library, a National Historic Landmark and the centerpiece of the campus, is listed for its architectural significance. Philosophy Hall is listed as the site of the invention of FM radio. Also listed is Pupin Hall, another National Historic Landmark, which houses the physics and astronomy departments. Here …
