Some interpret it as Minas Morgul (with the moon over it as it used to be the
Tower of the Moon) and Minas Tirith (with the sun over it as it used to be
Minas Anor, the Tower of the Sun).
As NZ Strider pointed out, it was in his letter #143 to Raynor Unwin he said:
"I am not at all happy about the title, "The Two Towers". It must
if there is any real reference in it to Vol. II refer to Orthanc and the Tower
of Cirith Ungol. But since there is so much made of the basic opposition
of the Dark Tower and Minas Tirith, that seems very misleading. There is,
ov couse, actually no real connecting link between Books III and IV, when cut
off and presented separtely as a volume."
I think the only thing we can be fairly sure of is that Tolkien did an
excellent job of never letting himself be pinned down as to the answer!
There's a link to his TTT cover below. (It is a little slow to
load).
"I don't suffer from insanity...I enjoy every minute of it!"
