Some 4 miles north of Beaumaris, Penmon provides a glimpse of Anglesey's long spiritual significance. An early Celtic monastery was established here in the 6th century by St Seiriol. Burnt down by the Danes in 971, its last relic is the basin of the holy well, tucked behind the current stone church. The earliest extant parts of that church include two 10th-century Celtic crosses, a font from around the turn of the 2nd millennium and some wonderful 12th-century Romanesque arches.
The Augustinian priory that took over the site in the 13th century survived until dissolution in 1536. The buildings then fell into ruin, with the exception of the church, which is still used as a parish church to this day. Once the monks were turfed out, the land was taken over by Beaumaris' leading family, the Bulkeleys, who, in 1600, built the gigantic dovecote that stands nearby. Pigeons, used for their meat and eggs, would enter through the cupola and roost in the 930 holes. Opposite the dovecote is a path leading to St Seiriol's Well, the reason why the priory was built on this very spot.