We don’t have any longwave stations in this country, other than the governments failed attempt at using long wave (WGU-20) for emergency communications in the 1970s and 80s. In Europe, Longwave continues to be used, mainly because of its excellent ground wave propagation can cover large distances without fading or interference. Several have closed in recent years due to the expense of maintaining tall radio towers and higher quality programming sources.
This is a video of the transmitter site for Atlantic 252 in Ireland. Atlantic 252 went defunct in 2001, however, the frequency is still in use by RTE radio 1.
500KW is quite a bit of power. The antenna mast is 248 meters, or 813 feet tall. Interestingly, RTE discontinued service on MW (AKA AM broadcast or standard broadcast) but left this signal on the air. Reportedly, this station has less power but better coverage.
This is a radio station database of all Longwave (LW), Medium wave (MW) and Tropical bands stations worldwide. You can browse frequency and location lists, search for stations, and get technical information. If you register, you can use a online logbook, create bandscans, and provide update information to the database editors. This is a free, open and non-commercial hobby project which depends on the cooperation of many individuals.
For LW/MW DXer’s this is a good information source.