Hello Time-Nuts, As part of the 100th anniversary of WWV celebration there were some tours of the NIST facility offered. Of course I had to take them up on this opportunity! It was a fun couple of hours. Started out in the old time scale building (Bldg 1) and saw the back-up UTC (NIST) time scale (which itself is fully redundant). Also got to see the maser room there as well. Next we moved to the new building (Bldg 81) and spent some time at cesium fountain NIST F-3. This unit is not their most accurate, but is their most reliable (with about 50% campaign up time). The room also has three hydrogen masers there. Then we visited the old cesium fountain F-1 which has been torn apart and an improved version is being assembled as NIST F-4. Then we visited the primary UTC(NIST) time scale (which is also fully redundant). We topped it all off with the Two Way Satellite Time Transfer (TWSTT) station used to compare UTC(NIST) with the rest of the world. It was a great opportunity to talk to the leaders of each of these efforts, and Mike Lombardi also accompanied us. It was great time-nut fun! I have attached some pictures. The one of F-3 is the fountain in one rack and electronics next to it, there is a whole optical table full of gear (not pictured) that drives all the optical fibers around the fountain. F-1 pictures are not great because it is a very tight space. One picture is of the fountain that has been assembled and baked out and is currently being leak tested. It will be mounted on the optical table on the right in the second picture. As with F-3 there is another whole optical table with the lasers, partially visible on the left in the pictures. The time scale picture is the primary unit, there is capability to compare 32 channels in the ensemble. Regards, Skip Withrow