Ffynnon Gwenfaen - Credit: Wikimedia Commons
St Gwenfaen's Well (also known as , and ) is an early medieval holy well in the south west of Holy Island, Anglesey, named after St Gwenfaen, whose cloister was nearby. The site includes substantial remains of a building and is both a scheduled monument and a Grade II listed building. Traditionally, a gift of two white quartz pebbles thrown into the pool can cure mental health problems. Read more on Wikipedia
Source: en.wikipedia.org