The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
Happened as dated, per the source: "The Sphinx observatory ... was completed in 1937."
Wikipedia's infobox lists the Sphinx Observatory as "Established" in 1937, matching the pin's stored year exactly, though without further narrative detail.
The page could not be fetched, but its title identifies it as the Jungfraujoch railway operator's own official history page, the authoritative primary source for the Sphinx Observatory's 1937 completion the pin cites.[1]
Something missing or wrong? Say it in your own words: a link that backs this pin up, a different start or end date and why, or a fact it lacks or gets wrong. The AI checks it against this pin's sources, searches for better ones, and adds any page that backs you up. The pin's own sources still count most. A picture that shows something else, or shows it badly, is looked at too, and moved down or replaced.