In 1965, the Tryweryn Valley was flooded to create a reservoir for Liverpool and Wirral, destroying Capel Celyn village. Around 45 of the village’s 60-plus residents lost their homes. The post office, school, and chapel were all submerged.

In remembrance, Meic Stevens, a Welsh singer and songwriter, painted “Cofiwch Dryweryn” (“Remember Tryweryn”) on an old ruined cottage wall. Ever since that day, the wall and slogan have become an iconic symbol of Welsh pride. The wall has been vandalized many times over its lifetime, but has always managed to bounce back.