Inspired by my thread yesterday on 'how to read a church', here's a very quick guide to the kinds of church architecture and decoration you're like to find across Europe - those that aren't modern atrocities, that is. Ok, here goes... 1/
ROMANESQUE - 10th - 12th centuries. Big. Imposing. Not so much decoration. Any decoration may be geometric designs. Lots of arches. Very imposing. Churches doubled as fortifications in some areas. Quite dour. Here's Mont St Michel Abbey in Normandy, France. 
GOTHIC - 12th - 15th centuries. Big, flamboyant. People worked out how to use support mechanisms, such as the flying buttress, to create high naves and soaring towers. More space, more room to whack statues and carved decoration. Here's Notre Dame de Strasbourg, Alsace, France.
It should be noted that there are various 'flavours' of Gothic, based on time and location, and people did the best with the materials they had at hand to put their own spin on the style. Here's the Frauenkirche in Nuremberg, a brick Gothic church.
RENAISSANCE 15th -16th centuries. Everybody winds their heads in a bit, and decides to start ripping off Greece and Rome again. Churches sprout up in all sizes and shapes. St Peter's Basilica in Rome, Italy, without all the gaudy bits, is quite Renaissance in style.
It should be noted that the Renaissance saw the Protestant Reformation, ushering in a way of iconoclasm across northern Europe. Basically, people went in and smashed everything up, whitewashing walls. Interiors started looking like the Stiftskirche in Herrenberg, Germany.
BAROQUE 16 - 18th centuries. The Catholic Church strikes back. They take the classical style in vague, and slather it with ornamentation & colour. Everything is monumental, seemingly wrought in one piece. The mission here is to impress. Here's the Karlskirche in Vienna, Austria.
ROCOCO - 18th century. Baroque has a mid-life crisis, gets botox injections, does a lot of coke and gets an 18 year old girlfriend. Everything is theatrical & very much over the top. Almost blinding. Here's the Asamkirche in Munich, Germany.
Seriously, Rococo is one of the most entertaining church architecture & decor styles out there. Absolutely ludicrous. Kanye jacked it for his 'Power' clip. I simply can't get enough of it when I'm feeling down. Here's Birnau Basilica on Lake Constance in Germany.
After this, styles start to get recycled in a big way, although the Art Nouveau period sees some pretty interest things done with churches. I used to live near a church that showed heavy, heavy Art Nouveau influences - the Markuskirche, in Stuttgart, Germany.
I don't really know or care enough about modern styles of church construction to comment, but I'm happy to be surprised by unique or striking examples. Anyway, hope that was helpful in identifying those churches dotted around you! /FIN
