Every year since 2002, the city of Ottawa as well as a dedicated group of volunteers, organize Doors Open, an event that celebrates the city's building heritage, architecture and design. This year, on June 4th & 5th, several buildings, such as the Delegation of the Ismaili Imamat, the Shenkman Arts Centre and the Embassy of France, will open their door to visitors.
A full list of the participating buildings are included on the city's website. There's also a handy Google map to help plan the day. I doubt it would be possible to see them all in two days, but there are certainly a lot of interesting modern buildings on the list. Not to mention a Geocache event going on at the same time.
Photos : City of Ottawa | Informatics | Flickr | French Embassy