Sparkfun member Nate shared an amazing Digital clock synchronized with GPS receiver having an accuracy of 100ns. You can build your own GPS based clock that displays time in the format of HH:MM:SS. The software Firmware required for this project is available here! C ASM HEX
You can get the LED Light Bar here! These LED bars you can simply screw onto the wall in a 7-segment digit configuration. To get power to the light bars, you will need to run 12V to the + terminal and Ground to the – terminal. In addition you will require a controller board with GPS antenna. To build it, you can use a PIC16F877A and Lassen iQ GPS receiver module is the big silver block.
For other necessary details you can visit the link here: GPS Wall Clock