These four "finger-like" extensions to a Vienna restaurant, by PPAG Architects, feature mirrored walls that reflect the surrounding parkland, and windows that slide up above the roof (+ slideshow). More about PPAG Architects adds mirrored extension to restaurant in Vienna's Stadtpark
Hexagonal slate tiles cover this extension to a west London home designed by architects Christian Ducker and Tyeth Gundry to create a bright and spacious new kitchen (+ slideshow). More about Gundry and Ducker's Slate House is an extension clad with hexagonal tiles
This rust-coloured copper home extension by British studio Poulsom Middlehurst sits above the red-brick walls and clay-tiled roof of a Victorian terrace in east London. More about Poulsom Middlehurst adds copper-clad extension to east London attic flat
Architect Jochen Specht has doubled the size of a 1960s house in rural Austria by encasing its stone walls behind a new facade made up of dark timber, concrete and plenty of windows (+ slideshow). More about Jochen Specht envelops a 1960s house in a new timber and concrete facade
Wooden walls concertina across open-plan living areas to subdivide this renovated stone house and extension by Spanish office XLMS (+ slideshow). More about XLMS extends 19th-century stone house in Mallorca to create a holiday home
Australian studio Philip Stejskal Architecture has equipped a white timber extension to a 1890s duplex with shutters and sliding panels that camouflage with the walls when closed. More about House by Philip Stejskal can be "locked down" with shutters that blend into the facade
Hundreds of tiny holes puncture the white concrete panels that clad these two extensions to the Badajoz Fine Arts Museum by Spanish firm Estudio Arquitectura Hago (+ slideshow). More about Badajoz Fine Arts Museum extensions feature speckled walls and bevelled edges
A large window wraps around one corner of this brickwork extension to a Victorian house in London by local office Cousins and Cousins (+ slideshow). More about London house extension by Cousins and Cousins has a window wrapping its corner
Belgian firm Urbain Architectencollectief has refurbished a former brick fire station building and added an extra storey to house additional facilities for a cultural centre in the city of Kortrijk (+ slideshow). More about Urbain Architectencollectief converts brick fire station into Kortrijk cultural centre
News: Danish studio COBE has unveiled its designs for an extension to the Red Cross headquarters in Copenhagen, comprising a large triangular structure that rises up from the ground at an angle to meet the existing building. More about COBE reveals competition-winning Volunteer House design for Danish Red Cross
The upper storey of this brick extension to a mid-century home in north London by Lipton Plant Architects projects over the entrance to form a porch (+ slideshow). More about Lipton Plant Architects adds pale-brick extension to north London home
Pale wooden window frames contrast with the black-stained cedar facades of this extension to a detached house in Nantes by French studio Bertin Bichet Architectes (+ slideshow). More about Nantes house extension contrasts blackened wood facades with pale window frames
A glass-fronted stairwell joins a craggy stone Portuguese house to its new concrete extension by Filipe Pina + Maria Inês Costa (+ slideshow). More about Filipe Pina + Maria Inês Costa add concrete extension to stone house in Portugal
The steeply angled roofs of a wooden pavilion and extension by Bent Architects will screen a family home in Australia from a "monster" development on an adjoining plot of land (+ slideshow). More about Bent Architecture's wooden extension screens a Melbourne home from neighbouring "McMansion"
The street-facing elevation of this brick and steel extension to a 1920s Montreal property echoes the proportions of the original building, but at the rear a large angular outcrop projects over the back garden (+ slideshow). More about Steel cladding frames an offset window at Montreal house extension by Naturehumaine
A marble-lined steam room is squeezed below the sloping ceiling of this apartment extension in Lisbon by local studio Camarim Arquitectos (+ slideshow). More about Lisbon apartment extended by Camarim Arquitectos to include an attic steam room
Spanish studio MX_SI added vertical wooden mullions to the exterior of this museum extension in Mänttä, Finland, to evoke the trunks of trees in the surrounding park (+ slideshow). More about MX_SI's addition to the Serlachius Museum Gösta has a stripy facade based on an "abstract forest"
Italian studio Massimo Galeotti Architetto has filled in the empty corner of a house in Treviso with a timber-clad extension to provide space for a new music room (+ slideshow). More about Massimo Galeotti adds modern timber infill to the corner of an old Italian villa
A freestanding concrete staircase spirals between the floors of this timber-frame and stone building remodelled by the founders of A1 Architects to form their own home and studio in Prague (+ slideshow). More about Charred-timber extension by A1 Architects transforms an old cottage into a home and studio
Crinkled fibre-cement panels clad the facade of this theatre extension by Finnish studio ALA Architects in the city of Kuopio, complementing the concrete exterior of the original 1960s building (+ slideshow). More about ALA's Kuopio City Theatre extension features a crinkled facade