The aim of this study is to understand what makes a landmark more salient and to explore whether assessments of saliency vary between experts and non-experts. We hypothesize that non-experts' saliency judgments will agree with those of the experts. Secondly, we hypothesize that not only visual characteristics but also structural characteristics make landmarks salient and that the size and visibility of objects are important for them to be considered as salient. To test our hypotheses, an online navigation game, Sea Hero Quest (SHQ), was used and two levels of the game were selected as the case study. The characteristics of these levels were evaluated by non-experts and experts in the field. Our results suggest that both visual and structural characteristics of landmarks make them more salient. We also discovered that experts' saliency evaluations are mostly consistent with non-experts'.