The keywords are held in three levels. To do a search first select subjects or places from the drop down subjects list. From the level-1 keywords list select a topic i.e. from the subject list select Buildings, then from the level-2 keywords list select Churches and from the level-3 list select Baptist Chapel and then click on the search button to see all images on that subject. You may also select a time period by using the "Select a date period" box and then selecting from the period drop down box after you have made your subject selection.