Firstly let me nail my colours to the mast - I rather enjoyed David Gibbins earlier works, in fact this is the 3rd that I have bought. I've always been clear that they are somewhat limited, with incredibly annoying characters more than reminiscent of the Dirk Pitt adventures (I'm no fan of his either) The stories rely on the central protagonist having an in depth knowledge of every archeological dig / find ever, but you can forgive all of these short comings because when the adventure starts they really are good fun.
Now, I'm no best selling novelist, but I would imagine that when you come to your 3rd book you would look at what has worked in the previous 2 books and what hasn't worked, so in your 3rd book you add more of the former and remove some of the latter. In this way Gibbins has thrown us a curve ball - he has virtually removed all of the adventure and added page after page of tedious pseudo historical waffling.

I find it hard to understand how some of my fellow reviewers have stylised this as a page turner - I found myself on page 200 waiting for something to happen and ultimately made it to the final page with very little going on in between.

Things you need to know
Our hero is an all around good egg with ex girl friends working in every archeological dig in the world.
His side kick is very resourceful, tough and dependable, but fun.
Riddles that have lasted millennia can be deciphered in the course of less than a week, but only by the protagonist
A simple clue such as finding a coin minted in the time of the emperor Claudius will lead to an absolute deduction (correctly - surprise surprise) that the house we are in belonged to Claudius (I certainly have my limited edition stash of Charlie Mount coins ready for future generations to identify my home)
There will be absolutely no adventure - no sir - no way no how!
Despite the fact that the cover promises it and the protagonists remind us regularly there will be no menace, the bad guys will flit (very briefly) in and out of the prose, but will be about as menacing as my dogs favourite chew.

OK, you may have got the gist that I didn't enjoy this book, and joking aside it really is a shame. As I have already mentioned Gibbins earlier works were limited, but great fun and, so long as you don't want a historically accurate tale the they are to be recommended, but it seems that Mr Gibbins has run out of steam. His earlier books will make me try his next offering, but I sincerely hope that he has dropped the long prose, found another mechanism other than our hero's all around good guy ability to progress the plot and he has re embraced the rattling good passages of action that really hit me.