Tapered Sides

Source: wikipedia.org

Plan, Source: archdaily.com

Pirelli Tower, Milan, Italy, 1960 designed by Giò Ponti, Pier Luigi Nervi

Characterized by a bold structural skeleton, smooth refined curtain wall façades, and tapered sides like the bow of a ship, it was among the first skyscrapers to abandon the customary block form.

The architectural historian Hasan-Uddin Khan praised it as 'one of the most elegant tall buildings in the world' and as one of the 'few tall European buildings [that made] statements that added to the vocabulary of the skyscraper'.  -- Wikipedia

Read a post from ArchDaily
 

Source: wikipedia.org

MetLife Building(Formerly Pan Am Building), New York City, New York, USA, 1963 designed by Emery Roth & Sons with the assistance of Walter Gropius and Pietro Belluschi

the Pan Am Building is an example of an International style skyscraper. It is purely commercial in design with large floors, simple massing, and an absence of ornamentation inside or out. It has been popular with tenants, not least because of its location next to Grand Central Terminal. -- Wikipedia

 Source: © OT Paris / Fabian Charaffi

Tour Montparnasse, Paris, France, 1972 designed by Jean Saubot, Beaudouin, Cassan, de Marien

The tower's simple architecture, large proportions and monolithic appearance have been often criticised for being out of place in Paris's urban landscape and, as a result, two years after its completion, the construction of skyscrapers in the city centre was banned.  -- Wikipedia

Source: wikipedia.org

Alpha Tower, Birmingham, UK, 1973 designed by George Marsh of Richard Seifert & Partners

Source: RVDM archdaily.com

Plan, Source: archdaily.com

Housing In Aveiro, Glicínias, Aveiro, Portugal, 2007 designed by RVDM

This geometric deviation demands optimal structural solution to allow maximum flexibility to internal design. In order to achieve this goal, only four pillars appears each side of the elevators, allowing greater open space. Two external skins make the image of the twin blocks. The first one in glass makes big windows from floor to ceiling, extending perceived space towards the balconies. Metallic skin acts like a mask, providing privacy, solar control and noise reduction. -- ArchDaily

Source: Brett Boardman archdaily.com

Plan, Source: archdaily.com

Silk Apartments, Pyrmont, NSW, Australia designed by Tony Caro Architecture

It is a place of extraordinary contextual contrasts: the benign, north-east facing harbour setting and the complex south-west aspect with its attendant noise, privacy and environmental challenges. The buildings fan-shaped plan-form and divergent facade resolutions respond directly to these conditions. -- ArchDaily