At 700 metres, Llandudno Pier is Britain's longest, and unlike many of its peers it's survived in genuinely good condition. The walk out and back over the Irish Sea, with the Great Orme at one shoulder and the sweep of North Shore at the other, is one of the most satisfying free things you can do in North Wales.
The pier pavilion at the end hosts events and there's the usual seaside amusements if you want them. The views alone justify the walk.