I'm with Phatch - love Umberto Eco's books!
I cannot STAND Dan Brown's writing style - carelessly written at best. I honestly tried to read the Da Vinci Code - but found both his writing style and the storyline very derivative. He seems to have read hokum books on the Holy Grail by Gardiner and others - and just re-written in modern 'dialogue'. I never finished it!
I love Rosslyn Chapel and whilst the book has brought in much needed cash to effect repairs to the lovely little place, the surge in visitor numbers has to be seen to be believed. I actually saw a tourist trying to prise up a flagstone as he was 'sure' that was the hiding place of the Grail.

Tourists often have to be shhhshed during the services held there - even though there are HUGE signs posted in many languages, explaining that it is still used for religious services.
Edited to add: So, you'll have guessed that the answer to your question is NO!!!