The compliance with localisation standards and guidelines ensures the usability and suitability of web sites to multilingual and multicultural audiences. Considering the importance of cultural tourism in Italy, a web site that is usable and suitable to both local and international users can have a positive impact on visitors. From the general perception that localised versions present some limitations stems the decision to analyse and compare Italian and English home pages of museums web sites in one Italian region-Lombardy. The aim of this paper is to test whether Italian and English home pages respect usability guidelines and whether localisation has a negative impact on usability. Through the heuristic evaluation methodology, this paper presents a descriptive and critical analysis of aspects related to internationalisation, localisation, search in the web site, SEO and web accessibility in the two linguistic versions. Results show that over half of the home pages respect most of the usability guidelines checked, with differences between the two linguistic versions.