Question: what are the exhibition venues in Amsterdam that opened before 2004-10-15?
Answer(s):
answer: Van Gogh Museum Rietveld Building
answer: Rijksmuseum

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.0k3p)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.0k3p ns:travel.travel_destination.tourist_attractions ?x .
?x ns:exhibitions.exhibition_venue.exhibitions_at_this_venue ?c .
?c ns:exhibitions.exhibition_run.opened_on ?num .
FILTER (?num < "2004-10-15"^^xsd:dateTime) . 
}