architecture in the Da Vinci Code by Dan Brown.
introduction (see below for full list of locations from the book and the film)

Although very much a piece of fiction, it points out some very interesting pieces of European architecture, notably some ancient churches belonging to the Templars.

( The Knights Templar were a very interesting bunch, originally established as a fighting order of monks to protect pilgrims to the Holy Land.
They built a number of castles in Palestine and were well established in Jerusalem.
Their power and wealth increased rapidly in Europe where they built a number of churches, etc, during the twelfth century.
They eventually became too powerful and were accused of heresy and destroyed by the Church in the fourteenth century. It has been suggested by history that they indulged in the Occult, or at least in strangely unorthodox ceremonies. (the Freemasons of the seventeenth century supposedly subsequently based much of their secret ceremonies on old Templar rites).
And of course, as we all know, it has also been suggested that they are the protectors of the Holy Grail (the cup from which Christ drank at the Last Supper, said to lead to eternal life), because of the long occupation by the order of the Temple Mount in Jerusalem.

Anyway, the book taps into this. The intersting architecture is-

Rosslyn Chapel

A very interesting Templar church in Scotland from the fifteenth century. Incorporates a huge wall said to symbolise the western wailing wall of the Temple in Jerusalem. The interior is said to be rich in symbolism.

The Temple Church London

The Temple Church is a late 12th century church in London located between Fleet Street and the River Thames. It was originally constructed as the church of a monastic complex known as the Temple, the headquarters in England of the Knights Templar. In keeping with the traditions of the order, the nave of the church was constructed on a round design based on the
Church of the Holy Sepulchre in Jerusalem.

The order was very powerful in England during its existence. The Master of the Temple sat in parliament as primus baro (the first baron of the realm). The compound was regularly used as a residence by kings and by legates of the Pope. The temple also served as an early depository bank, sometimes in defiance of the Crown's wishes to seize the funds of nobles who had
entrusted their wealth there. The independence and wealth of the order throughout Europe is considered by most historians to
have been the primary cause of its eventual downfall .

Saint-Sulpice (Paris)

Not directly associated with the Templars. Saint-Sulpice has gained a peculiar mystique because the church is somehow associated with the supposed mysteries surrounding the "Priory of Sion", said to be a powerful, centuries-old covert order guarding some incredible secret (usually taken to be that the line of Merovingian kings survives into modern times; further
embellishment would make the Merovingians descendants of Jesus and Mary Magdalene).

Interestingly, the church appears to be associated with nature-worship.
The gnomon (in the background) and the brass line on the floor.
In 1727 Languet de Gercy, then priest of Saint-Sulpice, requested the construction of a gnomon in the church. It was made to help determine the time of the equinoxes and hence of Easter (since Easter Sunday is to be celebrated on the first Sunday following the full moon after the spring equinox). A meridian line of brass was made, running across the floor and then ascending a column or "obelisk" of white marble, nearly 11 meters high. In the south-end window a system of lenses was set up, so that a ray of sunlight shines onto the brass line. At the winter solstice (December 21), the ray of light touches the brass line on the obelisk. At the equinoxes (March 21 and September 21), the ray touches an oval plate of copper in the floor
near the altar.

Architecture from the book
I.M. Pei's Louvre Pyramid: one of the entrances to the galleries lies below the glass pyramid. Louvre-inversee.jpg (24419 bytes)
01- Musée du Louvre, Paris 1, Paris, France  25- La Pyramide Inversée 02- Temple Church, Temple, Holborn, London, England, UK
The Abbey's western façade The Apprentice's column.
03- Westminster Abbey, London  04- Rosslyn Chapel, Midlothian, Scotland, UK  05- Opus Dei Headquarters, New York
A drawing of Ezekiel's Visionary Temple from the Book of Ezekiel 40-47 The interior of the Church
16- The Temple in Jerusalem 18- Paris Meridian   19- Church of Saint-Sulpice (Paris)
Filming Locations for The Da Vinci Code (2006)
Belvoir Castle Spring Burghley House in 2004
06- Belvoir Castle, Belvoir, Leicestershire, England, UK 
(one of the Popes residences)
07- Burghley House, Stamford, Lincolnshire, England, UK  08- Caledonian Hilton Hotel, Edinburgh, Scotland, UK 
Click the picture to zoom it ! The Norman West Front of Lincoln Cathedral
09- Chateau de Villette, Condecourt, Val-d'Oise, France  10- Fairfield Halls, Croydon, Surrey, England, UK  11- Lincoln Cathedral, Lincoln, Lincolnshire, England, UK 
('Westminster Abbey')
View along the nave of Winchester Cathedral to the west door  
12- Ritz Hotel, Paris, France  13- Winchester Cathedral, Winchester, Hampshire, England  
14- Da Vinci Artwork 15- The Last Supper - Plot overview
US 1st edition cover Mary_Magdalene.jpg (7577 bytes)  
17- Notes on the story - Theological Notes on Mary Magdalene (external link) 20- The Illuminati
The Seal of the Knights — the two riders have been interpreted as a sign of poverty or the duality of monk/soldier.
rennes.jpg (79158 bytes)
21- The Knights Templar 22- The Priory of Scion 23- Rennes-le-Château