Bruder Claus Chapel is THE masterpiece by Peter Zumthor.
Its construction is quite spectacular: after building hand made formwork made out of 112 tree trunks, 24 layers of 50 cm concrete were poured over 24 days, in a technique that reminds the use of rammed earth.
Once the concrete was poured, the wooden frame was set on fire leaving a dark hollow cavity.
Glass cylinders were cast within the concrete, allowing light to filter inside. The result is spectacular and the feeling is that of standing in the middle of an old tree trunk which is covered in resin. It is just poetry at pure state.