古譚 is read as こたん (kotan) and means old tale.
こたん
kotan
ふるほん
secondhand book
こてん
classic (work, esp. book)
こだい
ancient times
ここん
ancient and modern times
ふるい
of the distant past
こもんじょ
pre-Meiji era document addressed to someone in particular
ふるもの
antique
こまい
old rice
こぼく
old tree
ふるでら
old temple
こじょう
old castle
こふう
old-fashioned