The Great Conservatory at Chatsworth, seat of the Dukes of Devonshire. I don't really care about nobility or the class system (probably because I'm on the wrong side of it), but I do lust after their absurd possessions, especially those that no longer exist.
Ah, 19th century conservatories ... how my heart flutters. This was largest in the world, and certainly one of the most lovely. See the ribbed surface, glass panes in a herringbone pattern? It was just shy of six stories high, 277 feet long, and 123 feet wide, heated entirely by coal. Carriage paths snaked through dense forest of plants, pools of water and magnificent fountains. Many of its plants had never before been seen in the western world. Rarest birds fluttered overhead.
One visitor described it as "a mountain of glass... an unexampled structure... like a sea of glass when the waves are settling and smoothing down after a storm," while the King of Saxony (no stranger to excess) dubbed it "a tropical scene with a glass sky."
Glass toys don't last. It was impossible to procure coal during WW1, leading to the death of the jungle within. I'm sure at that point it was wonderfully overgrown, a barbarous marvel, for the only thing better than a well ordered greenhouse is one that has gone to seed. Do you think the trees of the interior, tired of their confinement, broke their glass sky? I hope so.
University of Coimbra, Portugal: limed greenhouse with unruly tree.