Buckingham Palace opens to the public this weekend for summer tours and already tickets are selling at twice the pace as last year. The big draw? The dress Kate Middleton wore to wed Prince William is on display along with her tiara, earrings, shoes and wedding cake! The Guardian  reports that ticket sales have doubled this year.  Already 125-thousand advanced tickets have been sold and there's a feeling the tour may completely sell out - that's 600-thousand tickets.  The tour also includes 19 state rooms at the palace.