Argentina: The torch relay leg in Buenos Aires, Argentina, held on April 11, began with an artistic show at the Lola Mora amphitheatre in Costanera Sur. In the end of the show the mayor of Buenos Aires Mauricio Macri gave the torch to the first torchbearer, Carlos Espínola. The leg finished at the Buenos Aires Riding Club in the Palermo district, the last torchbearer being Gabriela Sabatini. The 13.8 km route included landmarks like the obelisk and Plaza de Mayo. The day was marked by several pro-Tibet protests, which included a giant banner reading "Free Tibet", and an alternative "human rights torch" that was lit by protesters and paraded along the route the flame was to take. Most of these protests were peaceful in nature, and the torch was not impeded. Chinese immigrants also turned out in support of the Games, but only minor scuffles were reported between both groups. Runners surrounded by rows of security carried the Olympic flame past thousands of jubilant Argentines in the most trouble-free torch relay in nearly a week. People showered the parade route with confetti as banks, government offices and businesses took an impromptu half-day holiday for the only Latin American stop on the flame's five-continent journey.

Answer this question, if possible (if impossible, reply "unanswerable"): Who was the mayor of Buenos Aires?
Mauricio Macri