The Advanced Technology Solar Telescope (ATST) is intended to be the next major step in ground based solar observatories. The ATST will provide a laboratory for ultra high resolution, polarimetric measurements of all layers of the solar atmosphere. Currently the project is preparing a conceptual design to fulfill this mission, including plans for the design, development, construction and operation of this facility. Given the nearly three-fold increase in aperture size over the largest existing solar facilities, our approach combines techniques from the newest solar facilities with lessons from recent nighttime telescope designs. This approach insures the ATST will meet the scientific goals that include diffraction-limited performance in the optical for high spatial resolution solar observations and very low scattered light to advance coronal observation capabilities. The current telescope design incorporates the latest active optics techniques, fast focal ratios for the primary optics, an open design for ventilation of locally produced seeing, an un-obscured off-axis pupil and a very high order adaptive optics system built into the telescope from the beginning. Examples of some of the current design concepts for the telescope structure, optics, thermal management, scattered light control, upgrade paths to multi-conjugate adaptive optics, software and facilities to support future potential upgrades and instrumentation are given along with some of the key challenges that lie ahead.The National Solar Observatory is sponsored and supported by the National Science Foundation.