Covering 350 hectares, the Costanera Sur ecological reserve is the biggest and most biodiverse green space in the city of Buenos Aires. Despite its proximity to the busy downtown area, with the skyscrapers of Puerto Madero in plain sight, it's a remarkably tranquil oasis of calm, and a haven for wildlife.
Along several winding paths leading to the Rio de la Plata river, and around three lagoons, you can observe different species of birds, mammals, reptiles and amphibians, as well as more than 500 species of native vegetation including meadows of pampas grass and forests of alder trees.
It's also a great place to unwind, and is one of the city's favourite spots for walking, running, cycling and family picnics.
The reserve is the unplanned result of an abandoned project to built a new adminstrative centre for the city by reclaiming land from the river. While the project was dropped, happily the city was left with a unique space that was taken over by nature.
In 1986, the area was declared a Natural Park and Reserve. It has since been recognised by BirdLife International and the Ramsar convention as an Important Bird Area because of the more than 300 species of native and visiting birds than have been spotted.
You can walk around the park in about an hour, or hire a bike near the entrance.