a suburban extension of Dublin city" and that its natural or "semi-natural" areas had shrunk from over 70% to around 40% of land area, while highly developed areas had risen from 14% to 30%. Flora and fauna As a semi-isolated area, Howth's flora and fauna have been studied in some detail, and a Flora of Howth, for example, was issued in 1887. Built heritage Howth Castle, and its estate, at least part of which is known as Deer Park, are key features of the area. Corr Castle also previously formed part of the estate. Aideen's Grave On the grounds of Howth Castle lies a collapsed megalithic dolmen (portal tomb), known locally as Aideen's Grave. Bailey Lighthouse At the southeast corner of Howth Head, in the area known as Bail(e)y (historically, the Green Bayley) is the automated Baily Lighthouse, successor to previous aids to navigation, at least as far back as the late 17th century. This is the subject of a picture, Howth Lighthouse, from the Needles, by George Petrie, which appears in Fisher's Drawing Room Scrap Book, 1835, with an attached poetical illustration by Letitia Elizabeth Landon. At the end of the East Pier of Howth Harbour are the Howth Harbour Lighthouse, built in the 19th century and no longer in service, and the pole-mounted light which replaced it. St. Mary's Church In Howth village are St. Mary's Church and its graveyard, overlooking the harbour. The earliest church on this site was built by Sitric, King of Dublin, in 1042. It was replaced around 1235 by a parish church, when that function was moved from the church on Ireland's Eye, and then, in the second, half of the 14th century, the present church was built. The building was modified in the 15th and 16th centuries, when the gables were raised, a bell-cote was built and a new porch and south door were added. The St. Lawrence family, of nearby Howth Castle, also modified the east end to act as a private chapel; inside is the tomb of Christopher St Lawrence, 2nd Baron Howth, who died in 1462, and his wife, Anna Plunkett of Ratoath. The College Also of historic interest is a building known as The College or The Old College, on Abbey Street which was primarily constructed in the late 15th or early 16th century but also with earlier medieval elements. Other structures Drumleck Castle on a promontory in