Valetta,Malta during the golden hour
The hypogeum in Malta, an ancient underground temple complex is one of the most amazing things I've ever seen. You need to book months ahead as they only take about 80 people a day down into the complex. one of the oldest temples in the world and very well preserved. They estimate it would have taken 1000 years to build and was carved out using animal antlers and rocks. Sophisticated architecture and it has a special acoustic effect where noises made into a central hole echo throughout the complex. It was 'audio engineered' by ancient builders to produce this effect.