Dunsink Observatory
Dublin, Ireland
The Dunsink Observatory is an astronomical observatory established in 1785 in the townland of Dunsink in the outskirts of the city of Dublin, Ireland. Directors of the observatory include William Rowan Hamilton, who, amongst other things, discovered quaternions, the first non-commutative algebra form, while walking from the observatory to the city with his wife. The annual Hamilton Walk that commemorates this discovery begins at the observatory.
Observatory data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).