From Elizabeth's birth onwards, the British Empire continued its transformation into the Commonwealth of Nations. By the time of her accession in 1952, her role as head of multiple independent states was already established. In 1953, the Queen and her husband embarked on a seven-month round-the-world tour, visiting 13 countries and covering more than 40,000 miles by land, sea and air. She became the first reigning monarch of Australia and New Zealand to visit those nations. During the tour, crowds were immense; three-quarters of the population of Australia were estimated to have seen her. Throughout her reign, the Queen has made hundreds of state visits to other countries and tours of the Commonwealth; she is the most widely travelled head of state.