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I've added two essays to the site on the topic of The Solomon Key, which were originally published over the past few months in magazines and websites. "Dan Brown and the Ku Klux Klan" looks at some strange connections between Washington, D.C., Freemasonry and the Ku Klux Klan, and throws up some wildcard ideas which might turn up in Dan Brown's next book. "Dan Brown - The Udjat and The Solomon Key" is probably a lot closer to the subject matter in DB's upcoming novel, as it finds some very strong connections between the Da Vinci Code web challenge, and the likely resources Dan Brown will be using for his research.
Don't forget also, that we have an entire chapter from The Guide to Dan Brown's The Solomon Key available online: "Strange Constructions" (see the bottom of that page for viewing options) peruses the location of The Solomon Key (Washington, D.C.) for esoteric and Masonic locations which will probably become the landscape for the plot (as Rome and Paris do in earlier novels). Even better, just buy the book already (details over to the right of this page)!