It looks like the rumor that Mentmore Towers in Buckinghamshire, UK would be used for the Wayne Manor in the film might be inaccurate. Scooper ‘storiva’ just wrote in with the following on Batman Begins…
‘Batman Begins’ is currently being filmed at Hatfield House / Hatfield Park in Hertfordshire, England. This is a (very) large old English manor house, set in huge grounds with woods surrounding. Michael Caine is one of the actors filming here, and rumour has it the Batmobile is going to make an appearance too.
Coincidentally, The Libertine is also being filmed here as we speak (for a few days), with John Malkovich and Johnny Depp.
You can check out pictures of Hatfield House by visiting the official website.