Ever since humans started building (about 10,000 years ago), settlers looking for sites to build new villages or homesteads have kept a simple list of criteria: access to water, proximity to arable land, and, ideally, as flat as possible. Modern development sites instead look for industry and transport links rather than water and farmland, but a level site is still the preferred option.
Whether you cut and fill into the landscape by digging in a retaining wall, or balance the structure above the hillside on stilt supports, building on sloping ground always adds time, cost, and difficulty to the project. With immense views and extra space both inside and out, however, the results can be worth the extra effort.
