In architecture, a keystone is the stone at the top of an arch. It is the supporting element for the entire arch— without it the arch would collapse. In the field of building architecture, the skills demanded of an architect range from the more complex, such as for a hospital or a stadium, to something simpler, such as planning simple residential houses. ... Isometric view of a typical arch An arch is a curved structure capable of spanning a space while supporting significant weight (e. ...
The keystone was also the logo of the Pennsylvania Railroad a railroad that operated throughout the northeastern and midwestern United States, Pennsylvania being known as the "keystone state." 1911 map The Pennsylvania Railroad (AAR reporting mark PRR) was an American railroad existing 1846–1968, after which it merged into Penn Central Transportation. ... State nickname: The Keystone State Official languages None Capital Harrisburg Largest city Philadelphia Governor Ed Rendell (D) Senators Arlen Specter (R) Rick Santorum (R) Area - Total - % water Ranked 33rd 119,283 km² 2. ...
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