  Galactic supernova remnants (SNRs) with angular dimensions greater than a few
degrees are relatively rare, as are remnants located more than ten degrees off
the Galactic plane. Here we report the results of a UV and optical
investigation of two previously suspected SNRs that are more than ~10 degrees
in both angular diameter and Galactic latitude. One is the proposed G354-33
remnant discovered in 2008 through 1420 MHz polarization maps. GALEX far UV
(FUV) emission and H$\alpha$ mosaics show the object's radio emission
coincident with a nearly continuous 11 x 14 degree shell of thin UV filaments
which surround a broad H$\alpha$ emission ring. Another proposed high latitude
SNR is the enormous 20 x 26 degree Antlia nebula (G275.5+18.4) discovered in
2002 through low-resolution all-sky H$\alpha$ images and ROSAT soft X-ray
emission. GALEX FUV image mosaics along with deep H$\alpha$ images and optical
spectra of several filaments indicate the presence of shocks throughout the
nebula with estimated shock velocities of 70 to over 100 km s$^{-1}$. We
conclude that both of these nebulae are bona fide SNRs with estimated ages less
than 10$^{5}$ yr despite their unusually large angular dimensions. Using FUV
and optical spectra and images, we also report finding an apparent new, high
latitude SNR (G249.2+24.4) approximately 2.8 x 4.2 degrees in size based on its
UV and optical emission properties.
