Michael Davitt was a strange choice for a bridge namesake by Victorian standards. He had lost an arm in a Lancashire cotton mill at age eleven, served seven years in English prisons as a Fenian, and founded the Irish National Land League in 1879 to challenge the very landlords who usually got buildings named after them. But in Mayo - Davitt's home county and the cradle of the Land League - he was already a hero by 1887. So when a Fermanagh philanthropist named John Grey Vesey Porter dug into his own pocket to cover the cost overruns on a new bridge to Achill, the Mayo County Surveyor's office knew exactly whose name to chisel on it. Davitt himself, then a Member of Parliament, came to open it. The original span was a steel bowstring girder, 120 feet long and just 8 feet wide - enough for the horse carts of a 19th-century island, not much more.

The 1887 bridge served Achill for 60 years before motor traffic finally ground it down. In 1947 the Mayo County Council commissioned J & C McGloughlin of Dublin to replace it, and the result - completed in 1949 - was at the time the largest bridge project ever undertaken by an Irish firm. That second bridge in turn lasted until 2007, when corrosion and a balky swing mechanism convinced the council to start over. The current bridge, designed by Malachy Walsh & Partners on a model inspired by the Spanish architect Santiago Calatrava, opened in 2008. Its 390 tonnes are still rotated by hand. For a few hours in November 2010 the new mechanism stuck open, snarling traffic for over two hours and reminding everyone that the simplest moving parts can have the most public consequences.

There is something quietly philosophical about a swing bridge. Achill is by every meaningful measure an island - 148 square kilometres of bog, cliff, and Atlantic shoreline - but for most of the day it is functionally a peninsula, joined to Corraun by an asphalt seam. When the bridge opens, the connection dissolves; a yacht slips through; the connection returns. Locals barely notice. Visitors stop their cars and lean on the rails to watch the sound move beneath them. Below, the tide funnels through one of the narrower channels on the Wild Atlantic Way, fast and cold and brown with peat from the bogs upstream. The bridge celebrated its 130th anniversary on 3 September 2017, counting all three generations as a single continuous crossing.

The west end of the bridge lands on Achill Island; the east end on the mainland at Achill Sound village. On either approach, the granite hills of the Corraun Peninsula and the long quartzite ridge of Slievemore frame the view. The current span - white-painted, cable-stayed, modern - looks nothing like the 1887 original, but the alignment is essentially the same. Drive across slowly. The cars behind you will understand. Everyone slows on this bridge.