The concept idea is the wish to design a building that merges and integrates itself with the natural environment. The choice to merge with the surrounding nature, doesn't implicate the renouncement to the expression of the artificial character of the architectural design, that is expressly declared in the technological materials (glass and steel) and in the constructive choices. The unities will be high energetic efficiency and eco-compatible.The bond between architecture and natural environment is perfectly expressed by the "pebble shape" of the two unities: a not-symmetrical and defective form, 7 mt maximum height, that underline the feeling to be in front of a natural element. The two unities, located in a hilly area, conform to the geo-morphological characteristics of the ground, looking like two big rocks that integrate perfectly with the environs.The orientation and the disposition of the two unities, that insist on two adjoining parcel, guarantee the privacy of each unity and, at the same time, offer a broad sight toward the sea to both. The Pebble Houses, perfectly equal among them, develop on two levels for a total of 209 sm of covered surface. At the ground floor the kitchen, the living the closets area, while at the first floor the two single and a double rooms are located.The large French windows of the front provide air and light to three rooms of the first floor from which, thanks to the natural contours, is possible to enjoy the beautiful surrounding landscape. The large terrace (55 sm), leans out towards the sea, also acting as a porch to the ground floor.The shell has two holes in the roof, which help to give light and air to the interior (the stairwell and bathrooms), and a large side opening by the terrace.The recognition of the around characters is the indefeasible and binding premise of the design phase, carried out with the choice of an almost invisible architecture that wants merging with the environment, becoming an integral part of it.The relationship between nature and architecture is very strong: the building, due the materials and the geometry talks in unison with the context, creating a spatial and aesthetical continuum. Besides, the concept is born from the wish to create two high energetic efficiency unities, with a great eco-compatibility in comparison to a traditional construction (CO2 issues equal to zero, accordingly to Kyoto Protocol).The heating system of the building, even in winter, is entrusted to a radiant floor. The entire system is managed by home-automation (domotics), which detects in real time the energy balance by regulating the opening of air vents and air velocity within the tubes, ensuring uniform and stable climatic conditions throughout the building.