The Lady’s temples and shrines are called Grail Chapels and are only built on sites where the Lady herself has appeared to one of her worshippers. This is most often the site where a Questing Knight was allowed to drink from the Grail, becoming a Grail Knight.
As Grail Chapels are almost invariably built by the nobility, most are of stone and built in a soaring style dominated by pointed arches and large windows. Each Chapel is a single hall with a high ceiling, a door at one end, windows in the side walls, and a large window in the end opposite the door. Stained glass, depicting the Lady, her servants, and great deeds of chivalry, is the dominant form of decoration. All Grail Chapels face the Forest of Loren, home of the Fay Enchantress and the place where, most believe, the Grail Damsels are trained. In much of Bretonnia, then, they face southeast, which also means that a lot of sunlight falls on that side.
The main window is almost always a depiction of the Lady, but in particularly small or poor chapels it may depict the Grail or a fleur-de-lis. The windows are decorated in order, moving back along the Chapel from the main window. The window over the door is often in the shape of the fleur-de-lis and almost never glazed with stained glass.
Every Grail Chapel is supposed to be attended by a Grail Knight, who guards it, maintains it, and exemplifies the values of the Lady. In practice, many Grail Knights found Grail Chapels on the site where they themselves encounter the Lady, and thus there are far more Grail Chapels than Grail Knights. In addition, most Grail Knights spend their lives wandering the land and fighting evil or serving their lords. Only a few choose to spend their lives watching over a Grail Chapel. Many ageing Grail Knights may also watch over chapels, the most famous of these being the Hermit Knight of Malmont.
At an attended Chapel, the Grail Knight gives a short sermon every Ladyday (the name for Holiday in Bretonnia), and those who live nearby are expected to attend. Grail Knights are not selected for their oratorical abilities, but many feel that they ought to make an effort, and thus long, rambling, pointless sermons are extremely common. For the rest of the time, the Chapel is open to those who wish to pray or meditate, but the Knight prevents any lesser use of the building.
Some Chapels are attended by Grail and Battle Pilgrims, often venerating the reliquary of the Grail Knight who founded the Chapel. These operate in much the same way as those attended by Grail Knights, except that the sermons tend to be better; the leaders of Grail Pilgrims are chosen on the basis of oratorical ability.
A few Chapels are maintained by nobles who are not Grail Knights. These Chapels were generally founded by an ancestor of the nobles in question, and in some cases, the maintenance of a Chapel is one of the duties attached to a fief. A bare handful are attended by Grail Damsels and Prophetesses. These are the holiest of the Chapels and popular destinations for pilgrimage.
Many Grail Chapels, however, are unattended and uncared for. These buildings may fall into ruin or be used as storage areas by peasants. As stone buildings, they are normally the sturdiest structure in a village. Grail Knights frown on most such uses, with one exception. Peasants who take refuge from attackers in the Chapel are believed to be putting themselves under the protection of the Lady, an act of piety. It is rare for even these Chapels to fall into ruin, as stone buildings are durable and normally only fall apart completely when building materials are stolen from them. In Bretonnia, only nobles are allowed to build in stone, and no nobles would risk getting caught stealing building material from a Grail Chapel.
The holiest Grail Chapel in Bretonnia is the First Chapel, in the castle of Bordeleaux. Founded by Marcus of Bordeleaux, one of the Grail Companions, in the great hall where he was visited by the Lady, it set the architectural pattern for all future Chapels, but is unusual in facing west; the hall already existed. This Chapel is attended by a Grail Prophetess, at least three Grail Damsels, and at least two Grail Knights at all times. All of the greatest nobles of Bretonnia pay towards its upkeep, but the Duke of Bordeleaux willingly pays the largest share.
1 Warhammer Fantasy RPG 2nd ED -- Knights of the Grail