Read the novel "Enigma" by Robert Harris. It explores the art and mathematics of codebreaking and describes the endeavours of the boffins at Bletchley Park to break the German Enigma Code.
Try The Sixth Lamentation by William Broderick or The Assassini by Thomas Gifford . Both good ..much better than DVC ! He couldn't hold my attention past the first chapter.!
Or the Jonathan Argyll series by Iain Pears.
Or you might like The Flanders Panel by Arturo Perez-Reverte.
Although the Gifford and Reverte were published a while ago now but you should be able to get hold of them somewhere.
should have said I'm not a huge fan of Dan Brown as find his style of writing a bit immature, but like some of the topics he covers. however if you liked the DVC then try his other one Angels & Demons which has a similar theme.
I would defo suggest The Templar Legacy 2, it is great. Of course there is also the one that started it all off and got banned 'Holy blood Holy Grail' which has all the historical facts that DVC is based on. A bit heavy going, but its all in there! Dan Browns 'Angels and Demons' written before DVC is brilliant !!