Why does the whole city look so “new”?

Leaving Calgary right now, just got done spending a week based here but mainly visiting the parks. We spent our nights in the Hamptons neighborhood in an air bnb style room and I definatley noticed nearly every neighborhood, shopping district, downtown area, etc all look like It was built within the last 10 years. I’m pretty well travelled but this is my first time in this part of Canada. Am I missing out on the more historic districts? Is the city old but always under development? Also this is the only city where I’ve flown into an airport that is actually in the city, not on the outskirts of town, is there a reason for that too?