Concrete

Toronto's City Hall is a massive concrete structure. Oddly, so was all its furniture, which was included with the original design. 99% Invisible looks at this unconventional design choice, and the legacy of that furniture.

When you think of sidewalks, you most likely think of concrete. Though it makes up the vast majority of sidewalks, concrete isn't the only game in town.

As oil prices rise, so does the cost of asphalt. Concrete, historically more expensive, is now becoming a viable cost competitor. Because of its lighter shade, its also been shown to contribute less to climate change.

Advances in material development have brought to the market a new type of concrete that can bend under pressure and heal cracks with the addition of water.

Concrete in a Minneapolis bridge replacing that which collapsed in 2007 is made of a concoction that boasts less environmental impact and durability. And it's self-cleaning.