A Monumental Mason
A person that studies old monuments is a historian or archaeologist.
A "cobbler" is a person who mends shoes. It's kind of an old-fashioned saying, but still used and understood in both British and American English. Otherwise I suppose you could just say "shoe repairman".
An old person.
Old
A geriatric You call them elderly or an elder.
A Senior Citizen?
A "septuagenarian" is a person who is 70 through 79 years old.
quinquagenarian
Old
A one-hundred-year-old person can be called a Centenarian.
water is the most apropriate answer to this question because water is the only thing which can clean up the mess on the monuments especially the old ones =)
A person who is 60-69 years old is called a sexagenarian.