Revealing Chicago - Aerial photographs with captions, by Terry Evans. Requires Flash. Categorized by location and by theme. - http://www.revealingchicago.org/
Chicago Snapshot - Personal photo gallery and profile of the photographer. Primarily consists of Chicago and Hammond Indiana views, with an extensive section for the defunct Acme Steel coke plant. - http://www.chicagosnapshot.com/
1902 Chicago Folio and Atlas - Scanned maps and transcribed text from this long out-of-print first topography of the Chicago Region, written by William Alden and first published in 1902. - http://ebeltz.net/folio/chgofolio.html