When Pittsburgh-based PNC purchased Washington, D.C.'s, Riggs Bank last year, it acquired more than it was after. That's because Riggs Bank was "the bank of presidents," and its assets included an extensive historical archive.

Left behind in the Riggs archive are a treasure trove of old ledgers, signature books and personal checks written by some of the 23 presidents who banked there, as well as a number of other men and women who shaped American history.

Mary Beth Corrigan is the PNC/Riggs Bank archivist. She's in charge of the collection and says that everything is "clearly arranged," as you might expect at a bank.

Famous names, including John Tyler, James Buchanan, Alger Hiss, Brigham Young, Eleanor Roosevelt, Abraham Lincoln and Richard Nixon, all find themselves catalogued in the bank's subterranean vault.

Corrigan, an historian by training, has been working on the collection since she was hired by Riggs in 1998 to mine the archives, a job not yet finished.