San Nicolás is one of the neighbourhoods of the city of Buenos Aires, Argentina, sharing most of the city and national government structure with neighboring Montserrat and home to much of Buenos Aires' financial sector. It's seldom referred to as San Nicolás, but usually as El Centro ("City Centre"), and the part east of the 9 de Julio Avenue is known as Microcentro. The limits of the neighbourhood are the Córdoba, Callao, Rivadavia, La Rábida Norte and Eduardo Madero Avenues.