The Chartres Cathedral dates from the 12th and 13th centuries, although there have been 6 churches on the same spot. It took just 25 years to build after the previous church burned down in 1194, and has remained mostly unchanged since that time.
The lower half of the facade survives from the 11th century Romanesque church (you can tell the Romanesque style because it uses rounded, rather than pointed arches). The main door, the Portail Royal or "Royal Door" is richly sculpted with scenes from the life of Jesus Christ. The flanking towers are also Romanesque, although the upper part of the taller of the two spires is much more flamboyant and dates from the start of the 16th century.
These are pictures of the stained glass windows, although you can find better pictures on the web. There are 3 "rose" windows, which are the windows which have a flower pattern, and each has more windows below.
If you get the chance to go to Chartres to see this, we recommend a sunny day and take a pair of binoculars, so that you can get a closer look at these wonderful 12th and 13th century stained-glass windows.
One of the better websites with pictures is San Jose State which has pictures and discussions of all of the windows as well as the sculptures over and around each door.
The choir screen in the cathedral of Chartres is a carved monument, which is impressive and unique. Encircling the sanctuary, it is a huge sculpture depicting various religious scenes in an elegant ornamental artwork. The choir screen was constructed over a period of two hundred years and by various people. The choir screen remains a precious testimony of the French sculpture of the beginning of the Renaissance at the end of the reign of Louis XIV.
The construction of the choir screen started in 1513, in the last years of the reign of Louis XII, under the direction of architect Jehan de Beauce, who had just finished the construction of the northern church tower of the cathedral. The choir screen was designed to be crossed by daylight at the level of the large scenes on one side of the ambulatory and the other. Chapels lit by a clerestory were made between the walls of the screen. In 1529, the choir was fully closed: a few years later, the execution of the ornamentation of the base and the clerestory was completed. Started around 1516, the placement of the forty large groups in the cornices topped by carved baldaquins, ended in 1716 at the same time as the whole monument. From 1763 to 1789, the new laying out of the choir caused destruction and mutilation which deeply modified the structure and the aspect of the screen: closing at the back of the niches, openings in the clerestory and suppression of small statues turned towards the inside of the sanctuary. The choir screen went through the revolutionary period without important damage and is today such as it was at the end of the 18th century.
This picture is that of the very ornate top.
This is a picture of one of the reliefs in the screen. The scene on the left is "The Circumsion" while that on the right is "The Adoration of the Magi". There is a great website which talks about it and shows each of the scenes with a description.
There is also this rather interesting Labyrinth on the floor. We didn't get a picture of it, but the website link gives information and a view of it.