  The symbol bootstrap has proven to be a powerful tool for calculating
polylogarithmic Feynman integrals and scattering amplitudes. In this letter, we
initiate the symbol bootstrap for elliptic Feynman integrals. Concretely, we
bootstrap the symbol of the twelve-point two-loop double-box integral in four
dimensions, which depends on nine dual-conformal cross ratios. We obtain the
symbol alphabet, which contains 100 logarithms as well as 9 simple elliptic
integrals, via a Schubert-type analysis, which we equally generalize to the
elliptic case. In particular, we find a compact, one-line formula for the
(2,2)-coproduct of the result.
