Using 3.7 years of Fermi-LAT data, we examine the diffuse 80-200 GeV emission in the inner Galaxy and find a resolved gamma-ray feature at 110-140 GeV. We model the spatial distribution of this emission with a ~3 degree FWHM Gaussian, finding a best fit position 1.5 degree West of the Galactic Center. Even better fits are obtained for off-center Einasto and power-law profiles, which are preferred over the null (no line) hypothesis by 6.5 sigma (5.0 sigma/5.4 sigma after trials factor correction for one/two line case) assuming an NFW density profile centered at (l, b)=(-1.5 degree, 0 degree) with a power index alpha=1.2. The energy spectrum of this structure is consistent with a single spectral line (at energy 127.0 +- 2.0 GeV with chi^2=4.48 for 4 d.o.f.). A pair of lines at 110.8 =- 0.4 GeV and 128.8 +- 2.7 GeV provides a marginally better fit (with chi^2=1.25 for 2 d.o.f.). The total luminosity of the structure is (3.2 +- 0.6) x 10^{35} reg/s, or 1.7 +- 0.4 x 10^{36} photons/sec. The energies in the two-line case are compatible with a 127.3 +- 2.7 GeV WIMP annihilating through gamma-gamma and gamma Z (with chi^2=1.67 for 3 d.o.f.).

We describe a possible change to the Fermi scan strategy that would accumulate S/N on spectral lines in the Galactic center 4 times as fast as the current survey strategy. Furthermore, we examine the co-added gamma-ray spectrum of unassociated point sources in the Second Fermi-LAT catalog (2FGL) using 3.9 years of LAT data. Using the SOURCE event class, we find evidence for lines at 111 GeV and 129 GeV with a local significance of 3.3 sigma based on a conservative estimate of the background at E>135 GeV. Other 2FGL sources analyzed in the same way do not show line emission at 111 GeV and 129 GeV. The line-emitting sources are mostly within 30 degrees of the Galactic plane, although this anisotropy may be a selection effect. If the double-line emission from these object is confirmed with future data, it will provide compelling support for the hypothesis that the Galactic center line signal is indeed from dark matter annihilation.