Piled Up 6

These are projects of terraced housing that were built into hillsides:

Source: Shozo Uchii

Sakura-dai-Court Village, Yokohama, Japan, 1970 designed by Shozo Uchii 

At Sakura-dai-Court Village, the diagonal form is continued although now the typical dwelling is an "ell"-shaped 5 room flat which is repeated as a connected series of party-wall, two and three story buildings. Here each apartment has a private entrance. The slope is steeper with the Court complex and the apartments are cantilevered out from the supporting piers to maximize buildable area with minimum foundations. -- Housing Prototype.org

More info from architect's web site

Source: Doctor Casino @ Flickr

Mühlehalde Terrace Housing, Umiken, Switzerland, 1971 designed by Metron, (Hans Scherer, Strickler & Weber)

This is one of the most elaborate and beautiful of the Swiss terrace housing designs of the 1950's and 60's. Built in several phases as an almost continuous building project between 1959 and 1971, this remarkable hillside of houses faces south looking across the Aare River.

These 30 houses are perhaps the best example of the kind of hillside housing for which the Swiss have developed a reputation for design excellence in the past half century following a national strategy of building housing on steep hillsides not suitable for agriculture. The houses at Umiken evolved during the course of several stages of design, however, the same idea of ell-shaped houses opening to wide, south-facing terraces is common to each stage of construction. -- Housing Prototype.org

Source: Housing Prototype.org

Pasadena Heights, Pasadena Heights (Mishima), Japan, 1974 designed by Kikutake, Kiyonori

About 150 terraced dwellings roughly follow the contours of the hillside, stepping down in 5 tiers on a south-facing slope. Several public stairs perpendicular to the slope connect terrace levels. At each terrace here is a wide pedestrian walkway from which entrance is made to each dwelling through a walled courtyard. . -- Housing Prototype.org

Source: HyojinYoo

Rokko Housing One, Rokko, Kobe, Japan, 1983 designed by Tadao Ando

this complex is wedged into a restricted site on a south-facing 60 degrees slope. Each of the 20 units is 5,4 x 4,8 m in size, and each has a terrace looking out towards the bush harbour of Kobe. Why was this monumental resident building so successful ? " I think architecture becomes interesting when it has a double character, that is, when it is as simple as possible but, at the same time as complex as possible"  -- ArchiTechno

More info from Ecole 

Source: ChaiSoo Ok archdaily.com

Seongbuk Gate Hills, Seoul, South Korea designed by Joel Sanders Architect and Haeahn Architecture

This project is located in the exclusive district of Seongbuk-dong, a neighborhood where precious traditional architecture and natural landscape is preserved and celebrated.

Presented with the challenge of a steeply sloping site, this enclave of 12 private houses is designed so that every residence possesses ample private outdoor space and unobstructed views of the landscape. From the scale of the site plan to the design of the individual units,the project weaves together building and landscape, natural and synthetic materials, and indoor and outdoor spaces. Each residence is 3,000 sf with a garage/entertainment level and two living levels. -- ArchDaily

Source: archdaily.com

4 Houses, Oslo, Norway designed by On Office

Working within the confines of a small site, the design of the stacked villas creates separate private gardens for each of the homes.  And, their orientation toward the river provides great views to the users.  Inside, the layout is simple and efficient, shaped to meet the landscape of the exterior.  -- ArchDaily