Plaza San Martín, a beautiful park at the base of Calle Florida in the Retiro neighborhood, is the nucleus of the Microcentro district. In summer months, Argentine businesspeople flock here during their lunch hours, loosening their ties, taking off some layers, and sunning themselves amid the plaza's flowering jacaranda trees. A monument to General José de San Martín towers over the scene. The park is busy at all hours, and the playground is often teeming with kids and their parents well after midnight. Plaza San Martín was once the location of choice for the most elite Porteño families at the beginning of the 20th century.