Tvísöngur (literally "two-song," for the traditional Icelandic harmonic singing form) is an outdoor sound sculpture installed on the steep hillside above Seyðisfjörður in 2012. Five concrete domes are arranged in an arc, each sized to resonate with one note of the pentatonic scale. The installation is designed to be experienced rather than just looked at — you step inside each dome and make sound, and the curved walls amplify and sustain it in ways that feel architectural and acoustic at once.
The walk up to Tvísöngur takes about fifteen minutes on a steep path from the main street. The views over the town and the fjord from the hillside are excellent in their own right. Go on a quiet morning when you have the place to yourself; the experience of sitting inside a resonating dome above a fjord valley, making noise with no one watching, is one of the more unusual pleasures available in Iceland.