Downtown Miami is experiencing a revival as young professionals and families move into residential towers that once sat mostly vacant amid the housing glut. Young professionals, who have moved into the area along with young families, often gather after work for food and happy hour at various restaurants and bars in Mary Brickell Village in Brickell. The Epic, a residential and hotel tower built in the heart of downtown Miami, is an example of the city’s real-estate rebound. When the market collapsed four years ago, many of the city’s glittering towers sat mostly vacant. Now the buildings are filling up faster than expected. Women relaxed at a spa at Icon Brickell, a luxurious three-tower complex. More than 80% of the units have been sold, according to Fortune International, which is in charge of marketing the building. Sales average 47 units per month.