Start your second day at the National Congress, site of the national legislature, and walk along Avenida de Mayo, one of the city's most famous avenues, which links the congress building with the executive governmental palace in Plaza de Mayo. Some of the city's grandest architecture can be found along this avenue, including the dome on the Inmobilaria building; the impressive Palacio Barolo, with its Divine Comedy symbolism, the historic Café Tortoni, with its marble tables, and finally the Art Nouveau shopping arcade pasaje Roverano.
At the end of Avenida de Mayo, you'll find yourself in the Plaza de Mayo, site of some of the most important events in Argentina's political and social history. Surrounding the square, you can see the pink governmental palace, the Casa Rosada, home of the national executive government, the whitewashed colonial Cabildo, where Argentina's first national government was formed, and the Metropolitan Cathedral, where Pope Francis led mass for many years as archbishop of Buenos Aires. The best point in the square from which to observe the surrounding buildings, is the Pirámide de Mayo, in the centre of the square.
From the centre of the Plaza de Mayo, walk three blocks along Calle Florida to Florida 165, between the streets Perón and Mitre. Here you'll find the beautiful Galería Güemes, an Art Nouveau arcade that offers a spectacular view of the city centre. There are many restaurants here where you can stop for a spot of lunch.
Continue along Florida, historically one of the city's most famous shopping streets, and the first to be pedestrianised. You can still find a wide variety of shops here, but one of the most luxurious places to shop is at the elegant, artistic Galerías Pacífico, at the junction with Avenida Córdoba. Pop in to take a look at the impressive painted dome, before you turn left and walk towards Avenida 9 de Julio, the avenue that boasts of being the widest in the world.
From the junction with 9 de Julio, you'll have a good view of the obelisk, one of the city's most iconic landmarks. You can take a closer look later, but for now, cross Avenida 9 de Julio (it'll will take you at least two changes of the lights!) and check out the breathtaking Colón Theatre. This venue is considered one of the world's best opera houses, and guided tours are available throughout the day, all year round. Opposite the theatre, is the Palace of Justice, site of Argentina's judiciary and Supreme Court, and an impressive example of French architecture.
Take bus number 5 in Libertad near where it crosses Avenida Córdoba, and in ten minutes you'll be at the junction of Maipú and Av. Santa Fe. Our next stop is Plaza San Martín, a lovely green space with trees and several important monuments. The square is named after Argentina's independence hero San Martín, who installed a mounted grenadiers regiment here in 1812. Here you can visit the Torre Monumental, a clock tower that was built by the city's British community, and the cenotaph to the fallen of the Malvinas War, and you can appreciate the Art Deco architecture of the Kavanagh building.
As the sun goes down, head south along Av. Leandro N. Alem seven blocks to Avenida Corrientes, which is famous for its theatres and nightlife. At the start of the avenue, you'll find Luna Park, a famous boxing venue, then, further along, some of the city's most popular pizzerias including El palacio de la pizza (Av. Corrientes 751), Las Cuartetas (Av. Corrientes 838), La Rey (Av. Corrientes 961), Banchero (Av. Corrientes 1300), Güerrín (Av. Corrientes 1368), Los Inmortales (Av. Corrientes 1369) o El Cuartito (Talcahuano 937).
If you fancy seeing a show at one of the many theatres on Corrientes, it's worth trying to book tickets in advance. All the same, there are so many shows, that's you'll usually be able to find something at late notice. Some of the most popular theatres are Teatro Metropolitan (Av. Corrientes 1343), Multiteatro (Av. Corrientes 1283), Broadway Theatre (Av. Corrientes 1155), Teatro Apolo (Av Corrientes 1372), Teatro Lola Membrives (Av. Corrientes 1280) and teatros del Paseo La Plaza (Av. Corrientes 1660).
You can buy tickets at half price at Tickets, the ticket office for theatre shows and musicals. The booth is located at the junction of Cerrito and Av. Roque Sáenz Peña (also known as Diagonal Norte), opposite the obelisk. It's open Wednesday - Saturday. More information.