From Colonia I took the ferry across the very wide river to Buenos Aires, where I stayed at the lovely Duque Hotel. I took a morning bus tour to get an overview, and also enjoyed the company of a volunteer greeter another day. For text start here: http://mytimetotravel.wordpress.com/2012/11/04/beginning-buenos-aires/
Impressive buildings surround Plaza de mayo
Impressive buildings surround Plaza de mayo