Wilson’s “Hyperbolic Obelisk” is a 32-foot tall tower with sides that curve slightly inward in the shape of a gentle hyperbola. In this photo the sun is just behind the obelisk, rendering it in silhouette.
https://files.mastodon.social/media_attachments/files/112/287/277/110/641/998/original/0f3fc442902be4d4.jpeg