The small white building on Calle Congreso is the most important historical site in Argentina. It was here that delegates gathered in 1816 to declare independence — an event reenacted every 9 July when the country pauses for its national holiday and the president traditionally addresses the nation from Tucumán. The interior is a museum of the independence movement, with portraits of the signatories, period furniture, and a sound-and-light show recreating the events of that summer.
The room where the declaration was signed is the building's centrepiece — a simple chamber with a long wooden table and high-backed chairs. Outside, a marble obelisk in the patio marks the spot. Free guided tours run throughout the day, and the building closes only briefly at lunchtime. Combine a visit with the cathedral and Plaza Independencia, all within five minutes' walk.