Palacio Paz is a beautiful mansion on Plaza San Martin in downtown Buenos Aires.

You can try to get a spot on their official guided tours but I find that these tours are hard to organize for tourists as it's typically in Spanish and spots usually go quick as locals are dying to see these locations. If you do what to try that, then send an email to: reservaspalaciopaz@gmail.com for more information.

How to see inside? It's easy. There's a cafe and restaurant with indoor and outdoor seating. Go for breakfast, lunch or merienda and dine in a palace. The restaurant is Croque Madame with is actually a chain. All of their locations are in epic locations like this. The food is good, not life changing, but that's ok because you're here for the location, not the sandwich.