Edinburgh Castle holds the distinction of being the most besieged place in Great Britain and one of the most attacked locations in the world. Historical records and archaeological evidence suggest it has been attacked or placed under siege at least 23 times throughout its long history. Its strategic position atop "Castle Rock," an extinct volcanic plug, made it an indispensable fortress during the Wars of Scottish Independence and the Jacobite risings. The most famous conflicts include the "Long Siege" of 1571–1573 and Oliver Cromwell's invasion in 1650. Because it was the symbolic heart of Scotland, control of the castle shifted between the Scots and the English many times. This turbulent history is why the castle today is a patchwork of architectural styles, as almost every generation of occupants had to rebuild or fortify the structures following a major assault or bombardment.