From the establishment of the first Dublin settlements through to the end of the seventeenth century, there was a constant cycle of demolishing and rebuilding of the buildings in the city. This means that little in the way of private housing from that era remains. There are however some public buildings and churches existing. Some, like Christ Church and St Patrick's Cathedrals were to undergo serious reconstruction by the Victorians, leaving little of their medieval fabric. Others like Dublin Castle were continually enlarged and redeveloped - and this has continued through to the twentieth century. Others buildings declined, like the Tholsel, and the City Walls and St Mary's Abbey of which very little remains. New complexes such as the Royal Hospital were constructed as Dublin developed into the basis of the city we have today.