The National Triangle was a significant feature of Walter Burley Griffin's Plan for Canberra. The apices of the triangle are Parliament House, the seat of government; the Defence Headquarters at Russell; and City Hill, representing the civilian part of Canberra. Griffin planned the city around two axes which converge in the centre of the National Triangle. The land axis connects Mount Ainslie, Capital Hill and Red Hill and extends off towards Mount Bimberi the Australian Capital Territory's highest mountain. The water axis runs at right angles to the land axis along the length of Lake Burley Griffin.