Among the greatest heritage buildings in Europe, cathedrals today enjoy massive attendance by both the faithful and tourists. Despite their long reverberation times, the large volume and majestic architecture of these buildings make them not only the perfect places for liturgical use but also for cultural purposes. This paper focuses on the acoustic study of the cathedral of Murcia (southeastern Spain), which has a Latin-cross plan divided into three naves with the choir located in the middle of the central nave. The cathedral has a Gothic interior with a reverberation time of 4.3 seconds at mid-range frequencies. In order to analyse the acoustic conditions perceived in the principal congregation area (mainly concentrated in the transept), both experimental and simulation techniques are employed. The acoustic conditions are determined by using the acoustic parameters described in the ISO 3382-1 and their acoustic mappings. Six source locations and two degrees of occupancy are considered to represent the different uses of the space. Results show that independently of source location, clarity and speech intelligibility values obtained in the audience area lie on the borderline of those considered required for good word/music transmission; ephemeral interventions and/or electroacoustic support are therefore necessary for recommended values of those parameters to be attained, especially when the degree of occupancy is low. Acoustic mappings, however, show a good distribution of sound in the space despite its shape complexity. The information gathered in this paper provides a valuable insight into the acoustics of this heritage building, which can prove highly useful in organising events held in this or other Spanish cathedrals with similar characteristics.