Question: Of the sights to see in Madrid, which is the earliest opened building?
Answer(s):
answer: Plaza Mayor, Madrid

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.056_y)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.056_y ns:travel.travel_destination.tourist_attractions ?x .
?x ns:architecture.structure.opened ?num .
}
ORDER BY ?num LIMIT 1