Sir Richard Arcos corrects Dr. Barton!

I was going to append this in a comment to Dr. Barton's last post, but then I decided it was too long. Just to note that the link between the emple Church and the Church of the Holy Sepulchre is more obvious when we remember that the Crusaders who conquered Jerusalem would have found a free standing rotunda, the 'Anastasis' of Constantine, rather than the current setting, where the rotunda is hemmed in by later building. I suggest that the polygonal churches were copied of the Dome of the Rock, while the round churches are copies of the Anastasis of Constantine (which the Dome of the Rock's architecture seems to pay homage to, remember the Dome was built by Greek and Syrian Christian builders for the Arabs).
On secret rituals. The ritual space referred to in Dr. Langdon's last book may have been used for Templar Chapters, which were held in secret. It was these secret chapters that the charges against the Templars alleged were the scene of much of the heretical activity, including the cats (which appeared magically in the closed space) and the idols. None of the charges alleged 'hieros gamos', the sexual activity mentioned in the charges being generally of a homoerotic nature, as in the charges against the Cathars. There is no verifiable evidence that these secret rooms were anything other than chapter houses in a few cases, and strongrooms in most cases. Remember, the Templars were simply dripping with boodle. An isolated report from Lincolnshire reported finding corpses and elements of esoteric ritual practices, but later investigation by archaeologists found none of this and identified the space as a treasure vault.

[Thanks, Sir Richard. Yes, I expect that the Temple Church in London is a copy of the Church of the Holy Sepulchre]