How to get the value of the document title in latex?

Using \@title does not work because \maketitle clears \@title. This seems silly to me but that’s the way it is. One solution is to redefine \title to save the title somewhere else. For instance,

\def\title#1{\gdef\@title{#1}\gdef\THETITLE{#1}}

then use \THETITLE.

You can do the other way around: \def\MYTITLE{...} then \title{\MYTITLE} and later use \MYTITLE again.