Quite possibly the oldest stereoview I have – I’d put this one at no later than 1870. This may have even been taken during the Civil War, although I think you’d have been hard pressed to find Pennsylvania Avenue that empty during the war. The area around the White House was even more the center of government at that time than it is now (now federal agencies are spread throughout the town and into the suburbs). The State Department was across the street to the north, and the War department was the other side of the White House. But Washington was a much smaller town in those days, and when Congress was not in session, half the town was empty.