Cliff House, San Francisco (Wikipedia)
The Cliff House is a neo-classical style building perched on the headland above the cliffs just north of Ocean Beach, in the Outer Richmond neighborhood of San Francisco, California. The building overlooks the site of the Sutro Baths ruins, Seal Rocks, and is part of the Golden Gate National Recreation Area, operated by the National Park Service (NPS). The Cliff House is owned by the NPS; the building’s terrace hosts a room-sized camera obscura.- Leonhard Euler (Wikipedia)
Leonhard Euler (/ˈɔɪlər/ OY-lər, German: [ˈleːɔnhaʁt ˈʔɔʏlɐ], Swiss Standard German: [ˈleːɔnhart ˈɔʏlər]; 15 April 1707 – 18 September 1783) was a Swiss mathematician, physicist, astronomer, geographer, logician, and engineer who founded the studies of graph theory and topology and made pioneering and influential discoveries in many other branches of mathematics such as analytic number theory, complex analysis, and infinitesimal calculus. He introduced much of modern mathematical terminology and notation, including the notion of a mathematical function. He is also known for his work in mechanics, fluid dynamics, optics, astronomy, and music theory.