The plaque on the Machynlleth clock tower, describing when constructed and why.
Wikipedia offers this description:
"To celebrate the 21st birthday of their eldest son, Viscount Castlereagh, the townspeople subscribed
to the erection (at the town's main road intersection) of the clock tower, which has become widely
known as the symbol of Machynlleth. The tower, which stands on the site of the old town hall, is the
first thing many visitors will notice. The foundation stone was laid on 15 July 1874 amid great festivities."