Byzantine and Christian:

http://lookuparchitecture.com/historybyzantine.htm

http://en.wikipedia.org/wiki/Byzantine_architecture

Romanesque:

http://en.wikipedia.org/wiki/Romanesque_architecture

Gothic:

http://en.wikipedia.org/wiki/Gothic_architecture

http://en.wikipedia.org/wiki/Italian_Gothic_architecture

Renaissance and Mannerist:

http://en.wikipedia.org/wiki/The_Renaissance

Rococo and Baroque:

http://www.visual-arts-cork.com/history-of-art/baroque-architecture.htm#arches

http://en.wikipedia.org/wiki/Architecture_of_Italy#Rococo_and_late_Baroque_century_architecture

Neoclassical:

http://en.wikipedia.org/wiki/Architecture_of_Italy#Neoclassical_and_19th_century_architecture