Answer: xiii

AnswerCrossword Clue
XIIIUnlucky number for Caesar?
XIIISquare root of CLXIX
XIIIMissing floor in Caesar's Palace?
XIIINumber not on a clock
XIIIConstitutional Amendment that abolished slavery
XIIIHour not found on a grandfather clock
XIIINumber not on a grandfather clock
XIIIChapter 13?
XIIINumber of one of the Olympics canceled due to W.W. II
XIIICicero's unlucky number
XIIINero's unlucky number?
XIIILouis called "The Just"
XIIIUnlucky number for Augustus?
XIIIUnlucky number, to Caesar?
XIIIUnlucky "numerus"
XIII13, in old Rome
XIIIAmendment abolishing slavery
XIIILowest number not found on a grandfather clock
XIIIRoman baker's dozen?
XIIIFactor of LXV
XIIICaesar's unlucky number?
XIIIUnlucky number, to Nero?
XIIIUnlucky number, in ancient Rome?
XIIIUnlucky Roman number?
XIIIVI plus VII
XIIIAmendment that ended slavery
XIIIIX plus IV
XIIINumber of chimes from a broken clock?
XIIIUnlucky "numerus"?
XIIIA French Louis.
XIIIChapter number.
XIIIChapter heading
XIIIA Louis
XIIIRoman baker's dozen
XIIIDecem et tres