About a 100 years. They did not work constantly on it, meaning that there were year long breaks between building phases. The first building was erected in 1031, but destroyed in an earthquake. So in the middle of the 12th century they started to build what you can see today. The last major adaption (not counting renovation work) was done in 1285.
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how long did it take to build the scottish parliment?
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hs2 will take 15 years to build
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it took 3 years
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