A longstanding light

The Irish Sea just off of Howth Head in County Dublin has long been notorious for shipwrecks, and a beacon has been planted on this promontory since the 17th century. Charles II commissioned the first, a simple square tower and coal-fired lamp. The next was built in 1814, a bit farther south and set lower to avoid being obscured by fog. This is the lighthouse that still stands today, though with many improvements added over the years—it's especially notable for being the first in Ireland to use a gas-powered beacon in the mid-19th century, and the last in the country to be automated, in 1996.