While there is no official "gatekeeper" dress code for the entire Montserrat mountain or its famous Cog Railway, there is a very strict etiquette for the Benedictine Monastery and the Basilica. As a significant religious site and home to the revered "Black Madonna," visitors are expected to dress respectfully when entering the sanctuary. This means your shoulders and knees must be covered; tank tops, sleeveless shirts, very short shorts, and mini-skirts are considered inappropriate. If you are visiting in the summer and wearing hiking gear, it is highly recommended to carry a lightweight shawl or scarf to wrap around yourself before stepping inside the church. Beyond the religious buildings, the "dress code" is purely practical: because of the mountain's high elevation (1,236 meters), it is often significantly cooler and windier than Barcelona. You should wear sturdy walking shoes if you plan to explore the hiking trails and bring a light jacket or sweater even on sunny days to stay comfortable in the changing mountain microclimate.