Today’s the big day. After months of rumors, ruminations, and really excited Tweets, Dan Brown’s The Lost Symbol has appeared in stores.

This follow-up to the best-selling Da Vinci Code and Angels and Demons is set in Washington, D.C. – though Brown’s version of D.C. promises to be more thrilling and fantastical than Georgetown University’s annual tuition and expenses.

Louis Bayard reviewed an advance copy for the Washington Post, and finds that the book will please readers who enjoyed the Da Vinci Code… mostly because of the similarity between the two stories:

Langdon has only a few hours to discover something that might not even exist: a Masonic pyramid that harbors the Ancient Mysteries, “a body of secret knowledge that was amassed long ago” and that “enables its practitioners to access powerful abilities that lie dormant in the human mind.” In quest of this mystic lore, Langdon confronts the usual battalion of public servants trying to stop him, but at his side stands the usual doughty female — older than usual — who, as a specialist in “Noetic Science,” even gets a chance to lecture him.

Otherwise, the “Da Vinci” template remains largely intact. Where, in the previous book, the savagery was committed by a massive albino monk, here it is committed by a massive tattooed monk.

Bayard also notes that the first printing run totaled 5 million copies, and “advance orders alone have made it the No. 1 title on Amazon for two weeks.”

In another Post story, two reporters follow the trail of Robert Langdon through his probe of the darker side of D.C.

David Montgomery and Monica Hesse recount their investigation,

After a night of frantic speed-reading, we’re ready to hit the pavement in search of Dan Brown’s Lost Symbol, armed with only coffee and a GPS. The book follows Robert Langdon and scientist sidekick Katherine Solomon as they race to solve an ancient Masonic puzzle before Langdon’s mentor is killed. It takes place in 12 hours, in a Washington very similar to our own (Except in Brown’s world, the Redskins are in the playoffs. What?!)