Complex sentence: The revival of the eisteddfod took place in Carmarthen in 1819 and the town hosted the National Eisteddfod in 1867,1911 and 1974 although, at least in 1974, the "Maes" was at Abergwili.
Split into simpler sentences: The revival of the eisteddfod as an institution took place in Carmarthen in 1819. The town hosted the National Eisteddfod in 1867,1911 and 1974, although at least in 1974, the "Maes" was at Abergwili.