Ensuring a website is accessible for diverse sets of users is a crucial and in some circumstances a legal requirement. It can also be a time consuming and frustrating fire fighting exercise. This research paper describes a visual evaluation of the accessibility of a website using Tree-Maps. Its goal is to highlight areas of a site that need attention. This is achieved by generating accessibility metrics and then plotting these onto a visualisation. The research identified that Tree-Maps can efficiently represent the accessibility of a website. Further work on the visualisation of changes in accessibility is suggested and discussed.