Edinburgh, June 4 : The Edinburgh Castle, one of Scotland's biggest tourist attractions, has launched a virtual tour of its secret passages via a new 3-D model. By the wonders of modern technology, virtual visitors can use the 3-D model to take an immersive digital tour of the castle, reports Xinhua news agency. The 3-D model, created by Historic Environment Scotland (HES), even gives virtual visitors a rare chance to explore the hidden parts of Scotland's most iconic fortress. "These digital innovations are crucial in helping to understand, conserve and tell the stories of our historic sites," said HES, the lead public body charged with caring for, protecting and promoting the historic environment of Scotland. Edinburgh Castle has stood on the high rock overlooking the Scottish capital city since the 12th century. It is the most visited attraction in Scotland, drawing about 2 million visitors a year. Currently, it is closed to visitors because of the COVID-19 pandemic. /IANS