James Fergusson 
Rude Stone Monuments in All Countries [PDF ebook] 

One of the most interesting of antiquarian studies is that which relates to the origin and purpose of the many ancient mounds and monuments found in almost every country. Antiquaries have never agreed whether the circles are temples or tombs or observatories, whether the dolmens are monuments of the dead or altars for sacrificing living men, and whether the mounds are tombs or law courts. This book compiles a Historical and Statistical account of the Rude Stone Monuments in all parts of the world.