Traditional canal houses in Amsterdam, The Netherlands at night. These particular houses are facing the Amstel river. At some points in Amsterdam history, the house were build slightly slanted forward, to allow lifting goods or furniture to the upper floors using a hook on the roof. However, this is not the only reason why the houses look so missaligned: the whole city of Amterdam was build over a swamp, where the soil is not very solid and yet the houses do not have uniformely distributed weight, all these factors making the houses leaning over time in certain directions. HDR image.