Built on the rugged cliffs of Holy Island, Wales, the South Stack Lighthouse stands watch over the deep waters of the Irish Sea. The 28-metres-tall white tower has guided sailors since its completion in 1809; it provides safe passage for ships on the Dublin-Holyhead-Liverpool route. When it was built, sperm whale oil was used to light the lamps; however, over the years, the mechanism has been upgraded to more advanced technology like LED bulbs and Fresnel lenses. Automated in 1984, the lighthouse continues to serve as a vital navigational aid, with its powerful beam shining up to 44 kilometres. As the sun sets and the sky fills with colours, the silhouette of the South Stack Lighthouse in the dusk makes for a stunning sight. Visitors brave the 400-step descent down the steep cliff face to explore the lighthouse, including its engine room and exhibition area.