Howth's harbour was built to be Dublin's gateway to Britain, and within two decades it had failed. The West Pier, raised between 1807 and 1813 to designs by the engineer John Rennie, was meant to shelter the Royal Mail packet boats bound for Holyhead. Silt defeated it. By 1826 the mail contract had moved south to Dún Laoghaire, and Howth settled back into fishing. Howth boat tours from Dublin tours now leave from that same granite quay, a working pier rather than a monument. Two kilometres offshore lies Ireland's Eye, Inis Mac Neasáin in Irish, named for the sons of a sixth-century saint. The island holds the ruin of St Nessan's church, a small stone oratory whose foundation is traditionally dated to the eighth century, and a Martello tower built around 1804 against a Napoleonic landing that never arrived. An Ireland's Eye boat tour passes close enough to pick out the tower's gun platform. Monks left for the mainland in the thirteenth century, taking the Garland of Howth, an illuminated gospel book now held at Trinity College Dublin. The rock itself is the oldest thing in the bay. Howth Head is Cambrian quartzite and shale, close to five hundred million years old, tilted and folded into the banded cliffs that a Dublin Bay coastal cruise reads like a cross-section. George Halpin's Baily Lighthouse has stood on the southeastern point since 1814; it was automated in March 1997, the last manned light station in Ireland to lose its keepers. North of it, the Nose of Howth drops to deep water, and the sea stack beside Ireland's Eye has carried a gannet colony since 1989, alongside guillemots, razorbills, kittiwakes and a resident population of grey seals. All of it sits inside the Dublin Bay UNESCO Biosphere, extended in 2015 to cover the whole bay. The coast matters now for reasons the Victorians would not have predicted. Howth Head has been protected by a Special Amenity Area Order since 1999, which froze development on the headland and left the cliff path, the Baily, the Martello towers and the heather above the Bog of the Frogs much as walkers found them a century ago. The East Pier carries its own history: Erskine Childers landed nine hundred Mauser rifles from the yacht Asgard here on 26 July 1914, in daylight, in front of a crowd. A Howth boat tours from Dublin tour reverses the usual vantage, so that the cliffs, the lighthouse and the island read as one continuous line, which no single stretch of the headland path can show.