City of Portland: When Every Structure in Town Was Built
This heat map looks like a work of art, but it actually shows the age of buildings in the Portland, Ore. area. About 544,000 structures are represented, including about 4,500 erected in the 1800s and 10,265 buildings constructed in 1978 alone. Justin Palmer created the heat maps based on public data released by the City of Portland.
There's a similar map for the nearly 10 million buildings in the Netherlands; some in central Amsterdam are more than 1,000 years old. This can help municipalities see which neighborhoods hold the greatest concentration of structures that may need repairs.