Freemasonry can be seen as a beautiful system of morality, veiled in allegory and illustrated by symbols. The symbolism is mainly, but not exclusively, drawn from the manual tools of stonemasons - the square and compasses, the level and plumb rule, and the trowel, among others. A moral lesson is attached to each of these tools... The meaning of the symbolism is taught and explored through ritual. - from Wikipedia
Here are some links to websites with information about Freemasonry.
33 symbols of the Scottish Rite degrees
Here are nicely done symbols for each of the 33 degrees of the ancient and Accepted Scottish rite of Freemasonry:
Masonic Lodge of Education
The Masonic Lodge of Education includes an extensive list of symbols and their meanings: (http://www.masonic-lodge-of-education.com/freemason-symbols.html).
The Masonic Apron
Each initiate, upon entering the Order, receives a symbolic apron, which is to be worn during all Masonic meetings and rituals.  This article shows the Masonic apron of Meriwether Lewis and explains the meaning of its rich symbolism.