  We report the design status and beam dynamics challenges for the
electron-positron branch of the Future Circular Collider (FCC) study, as of
August 2015. After recalling motivation and physics requirements for the
FCC-ee, we briefly discuss configurations and parameters, collider layout, the
superconducting RF system, possible staging scenarios, final-focus optics,
interaction-region (IR) issues, machine detector interface and IR synchrotron
radiation, dynamic aperture, beam-beam effects, top-up injection,
mono-chromatization option, impedances, instabilities, energy calibration and
polarization, and SuperKEKB as a key demonstrator, before presenting
conclusions and outlook.
