Some more books in this genre that I have read are the Daniel Knox series by Will Adams,
The Book of Air and Shadows by Michael Gruber and
People of the Book by Geraldine Brooks.
I really enjoyed the Ken Follett books mentioned, both the Pillars of the Earth series and the newer Century series. Although I wouldn't personally classify them as "Dan Brown" enigma-type thrillers. I still highly recommend them however!