San Telmo ("St Pedro González Telmo ") is one of the oldest barrios (neighborhoods) of Buenos Aires, Argentina.

San Telmo is one of the best preserved areas of the constantly changing Argentine metropolis, with a number of colonial houses and streets still paved with the original cobblestones (adoquines). San Telmo's many attractions include many old churches (e.g., San Pedro Telmo), museums, antique stores and a semi-permanent antique fair (Feria de Antiguedades) in the main public square, Plaza Dorrego . Tango-related activities for both locals and tourists also abound in the area.

A similar barrio is Pichincha, in Rosario city 300 Km north from Buenos Aires, with its own the antiques fair (Feria de Antiguedades Mercado Retro La Huella).