Hi Margaret,
The actual sentence is -
'....la magnifique ville de Québec, dont vous pourrez admirer les nombreux trésors architecturaux ....'
We use the relative pronoun 'dont' and in English you would use 'whose' -
'... the wonderful city of Quebec whose numerous architectural treasures you'll be able to admire...'
Take a look at the following Kwiziq lesson if you are not familiar with, dont -
Hope this helps!