and the buckingham palace there... 
how can both of them lying under the table solving the clue while the maid never notice they both were there?

Hmm.

I have yet to watch this sequel but I'm guessing there will be some let down in this one as it involves the White House and the kidnapping of the president. I can accept that they were able to steal the Declaration of Independence from the National Museum during the Gala Night in the first movie but kidnapping the president from the White House? I think it is only acceptable if Benjamin Gates possess Nightcrawler's mutant power like in X2: X-Men United.

Haha...

The original National Treasure sure hit the mark by showing us all the historical site of America and it was indeed a sightseeing movie apart from the adventure in the movie. I like the original movie but I'm clueless about this sequel and perhaps time will tell how well this movie did in the eyes and mind of the movie patrons!