CREATE TABLE table_37025 ("Year" FLOAT, "Competition" TEXT, "Venue" TEXT, "Position" TEXT, "Notes" TEXT)

Which Venue has a Notes of heptathlon, and a Year of 1991?
SELECT "Venue" FROM table_37025 WHERE "Notes" = 'heptathlon' AND "Year" = '1991'
SELECT "Venue" FROM "table_37025" WHERE "Notes" = 'heptathlon' AND "Year" = '1991'