...looking straight down and then westward over St. Louis from the top of the Gateway Arch. (If you look at the bottom corners of the photo, you'll see the two bases of this audacious structure, 640 ft/192 m below.)

The city is laid out on a grand scale, with a long corridor of monumentally-lined parkland reaching into the city from the Mississippi River. In the middle of the skyscrapers, the Old Courthouse (dating to the 1850's) was the scene of a pivotal court case leading up to the Civil War: Dred Scott. Slavery and westward expansion--inescapably important shapers of the U.S.

I was in St. Louis for a conference; mornings and late afternoons I was able to go for runs beneath the Arch in the park along the Mississippi River. On the last day of the conference, some colleagues and I took one of the claustrophobic elevator-pods up to the surprisingly small observation deck in the apex, with windows angled so you can look straight down over the empty space below.

(I only had my phone-camera with me; the above scene is stitched together from about eight or nine shots.)