Medieval Military 1000-1500
When the Normans conquered Britain in 1066 they needed to impose their authority over their new subjects. William the Conqueror knew what he wanted - strong, imposing castles that would strike fear into the hearts of any potential dissidents. The Tower of London's White Tower, begun shortly after William's arrival, is a perfect example of an angular Norman structure. The small windows, with their rounded tops, are typical of the period.

By the late 13th century, castle-building had moved on, although their purpose was much the same. Edward I had just subdued the Welsh and he wanted them to stay subdued. His design for Caernarfon Castle, begun in 1283, incorporated techniques borrowed from the Middle East, where he had travelled during the Crusades. Caernarfon Castle's vast walls - over 6 metres thick in some places - echo those of the great Roman walled city of Constantinople.

Gothic 1050-1400
Few Norman churches survive in Britain, Durham Cathedral is without doubt the finest. Although later towers were added, the original building was begun in 1093. In this area, rounded arches in the Norman style can be seen. But, because the cathedral was added to over time, visitors can also see elements of a later period of architecture, known as the Gothic style. It is characterised by tall, pointed arches which were stronger than rounded Norman arches.

Westminster Abbey is a good example of a Gothic Cathedral. the use of pointed arches means that the architects could introduce greater height into the design. It also meant that the windows could be larger, too. Very high buildings, lit by glorious shafts of natural light, proved to be ideal venues for worship on a grand scale.