  We report the detection of the two-dimensional structure of the radio source
associated with the Galactic Center black hole, Sagittarius A*, obtained from
Very Long Baseline Array (VLBA) observations at a wavelength of 7mm. The
intrinsic source is modeled as an elliptical Gaussian with major axis size 35.4
x 12.6 R_S in position angle 95 deg East of North. This morphology can be
interpreted in the context of both jet and accretion disk models for the radio
emission. There is supporting evidence in large angular-scale multi-wavelength
observations for both source models for a preferred axis near 95 deg. We also
place a maximum peak-to-peak change of 15% in the intrinsic major axis size
over five different epochs. Three observations were triggered by detection of
near infrared (NIR) flares and one was simultaneous with a large X-ray flare
detected by NuSTAR. The absence of simultaneous and quasi-simultaneous flares
indicates that not all high energy events produce variability at radio
wavelengths. This supports the conclusion that NIR and X-ray flares are
primarily due to electron excitation and not to an enhanced accretion rate onto
the black hole.
