Ottawa is a great town with lots to see and do. As a Canadian, there is something special about checking out Parliament Hill and everything associated with it.
Take a tour of the Parliament buildings.
WEB Be sure to time your visit to see the changing of the guards. Also, the evening show that is on during the summer is actually quite good.
Going into Gatineau is worth it for the Canadian Museum of Civilization.
HERE. The view of Ottawa from the back of the museum is the Million Dollar view.
Gatineau is also worth it for the casino if you are feeling gambly.
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Ottawa has plenty of excellent museums.
HERE. I particularly recommend the CMC, the War Museum and the National Gallery.
Other than that, check out the other things on the Hill like the Supreme Court, National Press Building, etc. Wander around the Byward Market for people watching, shopping, food and drink. The market can be a good place to party in the evenings.
Stroll along the canal. Eat a beavertail, some poutine and some smoked meat.