César Tort investigating the “House of the Faces” in Andalusia, Spain (1992).
His conclusion was that the case is a hoax, and published his findings in Skeptical Inquirer (the references of his work appear in the Wikipedia article linked above).
October 2012 clarification
“Chechar” is a family nickname which rhythms with my real name, “César”. It has nothing to do either with “Chechens” or with the “Chechar District” in Algeria. César is a Spanish name from the Latin, Caesar.