A while back, a user of the Gridpoint Atlas software informed me of a site I was not familiar with, the Omega transmitting station in Australia. Here’s the description of that facility from Wikipedia:
The Omega Transmitter is located near Woodside, Victoria, Australia at 38.481228°S 146.935294°E. It uses an umbrella antenna carried by a 432 metre high grounded lattice steel guyed mast. This mast is the highest construction in the southern hemisphere.
Construction of this station was originally planned to be built in New Zealand but after protests from anti-war protestors, it was built in Australia.
After the shutdown of the OMEGA navigation system, it was used until 2004 as a transmitter for orders to submarines on 13 kHz under the callsign VL3DEF. Until December 2008, it had been transmitting a 100 baud MSK modulated signal on 18.6 kHz. However, the station has been closed down and transmissions have now ceased. The tower remains, but the transmitting equipment is on display at the Port Albert Maritime Museum.
As you can see, when I plotted the Omega station, I found that it had been placed on a 7.5′ grid line that goes through the center of the tower.