The architecture of Ireland is one of the most visible features in the Irish countryside – with remains from all eras since the Stone Age abounding. Ireland is famous for its ruined and intact Norman and Anglo-Irish castles, small whitewashed thatched cottages and Georgian urban buildings. What are unaccountably somewhat less famous are the still complete Palladian and Rococo country houses which can be favourably compared to anything similar in northern Europe, and the country's many Gothic and neo-Gothic cathedrals and buildings. Despite the oft-times significant British and European influence, the fashion and trends of architecture have been adapted to suit the peculiarities of the particular location. In the late 20th century a new economic climate resulted in a renaissance of Irish culture and design, placing some of Ireland's cities, once again, at the cutting edge of modern architecture. Pre-Christian Ireland Grange stone circle is the largest such megalithic construction in Ireland. The earliest date from the Neolithic or late Stone Age. Megalithic tombs are relatively common, with court graves or court tombs being the oldest, some dating back to around 3500 BC. Such tombs consisted of a long chamber, with a large open area (or court) at the entrance. This "court" was generally marked out with standing stones, with the rest of the structure also built in stone. Passage tombs consisted of a central burial chamber, with a long passageway to the entrance. Again, standing stones were often used for the walls, with slabs of stone over the roof. Newgrange in particular is more interesting in that the inner chamber uses corbelling to span the roof. The chamber and passageway were usually contained in an earthen mound, with the chamber at the centre (Newgrange is again notable in having exterior stonework on the mound). Other notable passage graves are Knowth and Dowth, also in the Boyne Valley near Drogheda. From some time beginning around the Iron Age, Ireland has thousands of ring forts, or "raths". These consist of an earthen embankment around a central enclosure, sometimes sited on a raised mound. In some cases a souterrain (tunnel) forms part of the structure. These were built also as hill forts depending on the local terrain, or indeed promontory forts. Dún Aengus on the Aran Islands one of the best examples of these forts, which may have been occupied at various times, even in the mediaeval era. Early Christian Ireland One