Professor Ratigan's Lair, also called Ratigan's Lair, is the secret hideout of the nefarious Professor Ratigan, Basil of Baker Street's archnemisis. It is stationed in a wine cellar with the yellow letter R which represents the criminal mastermind's own name imprinted above the door, and serves as the home and base of operations of not just Ratigan, but also Fidget (before his turn to good), Ratigan's thugs and Felicia, Ratigan's enormous pet cat.
Inside the wine cellar is a grand throneroom-like structure that has lush magenta curtains, an elegant water fountain, a bucket with a filled champagne bottle, chandeliers with candles, mirrors on walls with candles above them, and stolen/collected treasures filled with gold and jewels next his golden pedal harp. At the center of the chamber is a seemingly regal red carpet leading up to Professor Ratigan's white wooden throne with pink leather seat that his logo on the chair's headstead. The entirety of the room is suited to Professor Ratigan's own taste and criminal lifestyle, making him feel like a king living at a palace in extravagant luxury.
It was also the place where Hiram Flaversham and Olivia Flaversham were taken after their capture by Fidget; subsequently, this was also the place where Basil and Dr. David Q. Dawson were captured and placed into Ratigan's death trap before they escaped with their lives.
After Professor Ratigan's demise, his own lair is presumed abandoned.