The lake island where Princess Diana is buried and a new museum dedicated to her memory will both be opened to public view at her family home Wednesday, which would have been her 37th birthday. Diana's brother, Earl Spencer, has opened the grounds of Althorp, in rural Northamptonshire, through Aug. 30. The burial island will be off-limits to visitors, and the exact location of the grave is not marked. But visitors will be able to stand at the water's edge, look at the house, tour a museum (built in former stables) and view Diana's schoolgirl letters, her princess outfits and her stunning 1981 silk bridal dress. Nearly 150,000 tickets -- called "invitations to visit" -- have been sold. (It is said some 2,000 are still available and that there is an active black market for the invitations.) The cost is $15 for adults, $12 for senior citizens and $8 for children.