Union Square in San Francisco, USA is a gift from the mayor of San Francisco to the city in 1850. Union Square is both a transportation hub in San Francisco and a famous shopping district. There are a variety of department stores, high-end boutiques, art galleries and salons nearby, so you can make sightseeing and shopping.
From San Francisco Airport, you can take Bart to the city and go straight to Union Square. The square is not big, surrounded by high-rise buildings, with a tall pillar in the middle, standing on the sculpture of the goddess of victory. This square seems to be related to the Civil War. No doubt, it is one of the most important places in the city with lots of shops on every corner (including the famous Apple Store and luxury brands). It's brilliant for shopping.