Buenos Aires is a great place to visit or live in, especially when you are interested in architecture photography. For most parts of the year the weather in Buenos Aires is rather pleasing, but when it rains, it rains cats and dogs. For those rainy days, here are my top 5 places to visit and take pictures of (in not particular order).
Teatro Colon is the main opera house in Buenos Aires and is considered one of the world best concert venues. The only way to visit Teatro Colon is through guided tours (or buying a tickets for one of the shows).
Bonus Tip: If you are on a budget, there are free concerts in Teatro Colon. The happen twice a month on a Sundays. You have to pickup the tickets on the Friday before. This allows you visit the inside of Teatro Colon and getting a taste of the excellent sound quality.
Palacio Paz is a hidden treasure. Not many people know about it or have visited it. Palacio Paz was a mansion which was owned by a former newspaper owner. The interior of the building is still in original condition. It does not contain any furniture but the rooms and are still impressive enough. You can only visit the building with a guided tour. There are not too many tours and the tours only happened when there are at least 4 people attending it.
Bonus Tip: You can and should bring a Tripod.
Bonus Tip: Before/after visiting Palacio Paz visit the armory museum (i.e., 'Museo de Armas de La Nación'). It is right in the corner of Palacio Paz and well worth visiting.
Centro Cultural Kirchner
Centro Cultural Kirchner is a cultural center which is hosted within the old postal office of Buenos Aires. It features various exhibitions which change over time. The most impressive feature is the 'floating' concert hall inside the center of the building. To visit this part of the building you need to be part of a guided tour. Guided tours are free, but there a normally quite are lot of people wanting to take a guided tour. Plan on spending some extra time there. While waiting for your tour to start, you can explore most of the building/exhibitions on your own.
Congreso de la Nación Argentina
Congreso de la Nación Argentina is the where the Argentine parliament resides. There are free guided tours to visit building. You need to enter the building through a side entrance (close to the subte/metro station). The availability of tours depends on the sessions in the plenum. If the tour takes place you will see the plenum as well as the congress library.
NOTE: Do not forget to bring your passport. While the tours are free to enter you need a valid identification.
Palacio Barolo is another building that will catch your eye. It is just a 5 minute walk from the Congreso de la Nación Argentina. The build is extreme high and offers a magnificent view of the city and in particular the Congreso. Inside it offers impressive entrance hall, some antique elevators and many fancy hallways. One of the most outstanding features is the lighthouse on-top of its tower.
To visit Palacio Barolo you need to book a guided tour with http://www.palaciobarolotours.com. I recommend that you book their photography tour. The photography tour is identical to the normal 1 hour tour, but it is stretched to 2 hours to give participants enough time to take all the pictures they want.
Bonus Tip: You can and should bring your tripod.