I took a bunch of photos, and they mostly sucked, but I was reasonably happy with these ten. One of the photos shows the air conditioning vents under each seat. These worked using huge blocks of ice in natural caves under the building, making the theatre one of the earliest buildings to have air conditioning. It was pretty muggy in Budapest, so I imagine these vents must have been a God-send for corseted opera-goers.
In Vienna, we mostly took photos of the Prater (a big fun fair) and the Naschmarkt.