There is a resemblance to #42. I thought of big events that would use something of that shape and size, but earlier than the one in #42. Thanks to Wikipedia, I could start in Athens and proceed. Thanks to wagga, he did not force many iterations.
You might be on the right track for where... but what?
There was a major international event at that site in the last year of the 19th century. A certain baron was involved and later commented that it was amazing that the institution he founded survived that particular staging.