Built by the Spanish in the 17th Century, Castillo de San Marcos is a prominent feature of St. Augustine's coastline in Florida. It's the oldest surviving fortress in North America located in the oldest European-founded city. It's walls are made of coquina, a native stone. It's changed national hands a number of times and is reputed to be haunted as well. In addition, I've posted a Brazilain Daiquiri recipe included for summertime!