Answer based on context:

World Expos are also massive in scale, sometimes 300 or 400 hectares in size (Montreals Expo 67 was 410 hectares, Osakas Expo 70 was 330 hectares, Sevilles Seville Expo 92 was 215 hectares and Shanghais Expo 2010, 528 hectares). Pavilions participating at a World Expo can also be large, sometimes 5,000 to 10,000 square metres in size, mini city blocks in themselves and sometimes more than several stories in height. (The Australia Pavilion for Shanghai 2010 was 5,000 square metres, the British Pavilion sat on a 6,000 square metres lot, as did the Canadian Pavilion. The flagship Chinese National Pavilion had 20,000 square metres of exhibition space.)

Which expos were more than 400 hectares?
Montreals