I've been thinking for a while of having an StB 'greatest hits' category, just to collect together those posts and sites which seem to have the most impact, at least to me. One entry would definitely be the Cathedral of Lyon, France. Sometimes just remembering it makes me feel all better inside. I hope it can have the same effect on others.
The Basilica of St. Denis is one of my favorite French churches. It has at least three claims to fame: (1) It was the first church to have been built in the Gothic style. (2) It was the place where the coronations of most French monarchs took place. (3) It is the burial site of nearly all French kings, and of many other French royals and nobles.
These are both from the wonderful Mapping Gothic France site. That site has a set of several pages devoted to St. Martin's. Apart from the panoramas, there are a brief history and nearly 100 additional images of the interior and the exterior of the church.
Here's a remarkable page with photos of beautiful chapels, and a few churches, in both Europe and North America. You'll probably notice, as I did, that as you move down the page, it just gets better and better.
Here's a list of the houses of worship listed:
Palatine Chapel, Aachen / Aix
Sainte Chappelle, Paris
Chapelle de Rosaire de Vence (Matisse Chapel)
King's College chapel, Cambridge
Queen's Chapel, London
St. George's Chapel, Windsor Castle
Roslyn Chapel, Scotland
St. Salvator's Chapel, St. Andrew's University
Brancacci Chapel, Florence
Magi Chapel, Florence
Medici Chapels, Florence
Sassetti Chapel [Florence?
Monza Cathedral, near Milan
Cappella Palatina, Palermo
Contravelli Chapel, Rome
Sistine Chapel, Rome
Belvidere Chapel, Belvidere, Illinois
Duke Chapel, North Carolina
Heinz Memorial Chapel, Pittsburgh, Pennsylvania
Naval Academy Chapel, Anapolis, Maryland
Rothko Chapel, Houston, Texas
St. Joan of Arc Chapel, Milwaukee, Wisconsin
Thorncrown Chapel, Arkansas