Near the Design District, yet another mixed-use project is in the works. Alta Developers plans to build a project called Quadro at 3900 Biscayne. The site was once the home of WPLG-Channel 10, and sold last year for $18.36 million. Quadro will include 198 rental apartments and 28,000 square feet of commercial space. Leasing of the retail space is already underway.