The Port of Liverpool Building, the Cunard Building and, of course, the Liver Building are symbols of the city's rich maritime history and architectural innovation. However, there's one more impressive construction overlooking the Mersey which is another testament to Liverpool's structural advancement: the George's Dock Building. The Queensway Tunnel is celebrated as one of the greatest municipal achievements of the inter-war years. Merseytravel, which manages both the George's Dock Building and the Queensway Tunnel, organises tours of the site, giving the public a glimpse inside what tour guide Alison Smith calls the "fourth Grace" on Liverpool's waterfront. The ECHO was invited to take photographs of the interior of the building and the Mersey Tunnel below.