Mdc

16 clues
CLX x X
Four CD's
XL squared
Square of XL
Caesar's 1600
1600, to Cato
1600, to Caesar
1600, in old Rome
17th-century date
CD + CD + CD + CD
16th century's end
End of the 16th century
Year in Elizabeth I's reign
Year "As You Like It" debuted
Year in Pope Clement VIII's era
Pennsylvania Ave. address, to Julius