I found an 18000 piece Ravensburger “Skyline's of the World” puzzle, with all 4 bags still sealed, at a local thrift store for $5 today 🤗 : r/Jigsawpuzzles
Amazon.com: Ravensburger at The Waterhole - 18000 Piece Jigsaw Puzzle for Adults – Softclick Technology Means Pieces Fit Together Perfectly (17823) : Toys & Games
18000 Piece Puzzles – The Puzzle Collections
Amazon.com: Ravensburger Paradise Sunset 18,000 Piece Jigsaw Puzzle for Adults - 17824 - Handcrafted Tooling, Durable Blueboard, Every Piece Fits Together Perfectly : Toys & Games