The word moel is a common Welsh place-name element meaning 'a bare hill', while Fama is a variant on the personal name 'Mama', while Famau may refer to 'Mothers' - hence an interpretation of the name as 'Mothers' Hill'.
Sitting at the top of the hill is the Jubilee Tower, built to commemorate the golden jubilee of George III in 1810. It was designed like an Egyptian obelisk with three tiers (as you do). Although the foundation stone was laid in 1810 by George Kenyon, 2nd Baron Kenyon, the tower was never completed due to a lack of funds. In 1862, a major storm brought down the incomplete tower. The remaining upper part of the structure was demolished for safety reasons leaving just the base, which is still there today. Most of the rubble was removed from the site; smaller stonework was reused by local farmers for dry stone walls.
A northern part of the Offa's Dyke footpath, one of the UK's most popular National Trails, crosses the summit of Moel Famau and the Jubilee Tower. I was able to join the path at the carpark about 1 1/2 miles (2 km) from the summit.
Although somewhat overcast (no blue sky at all), it was a pleasant walk to the summit and back.