Veduta (Italian: 'view') describes highly detailed, topographically accurate paintings of cityscapes or landscapes — typically commissioned by wealthy travellers on the Grand Tour as visual souvenirs. The form flourished in 18th-century Venice, where Canaletto and Francesco Guardi met insatiable demand from British aristocrats who wanted accurate records of the city they had visited. Canaletto used a camera obscura to project scenes onto his canvas, tracing precise outlines before painting. His views of the Grand Canal and the Piazza San Marco are so topographically reliable that historians and architects use them as primary source material for studying how Venice looked before later modifications. The veduta is an ancestor of the photograph — and, arguably, the tourist postcard.