Century West Partners, a Los Angeles-based real estate developer, has started construction on Next On Lex, a $280-million mixed-use complex in Downtown Glendale. The project, located at the corner of Central Avenue and Lexington Drive, will feature 494 rental apartments and 8,140 square feet of ground-floor commercial space.  Citibank has signed on as an anchor retail tenant. Plans call for a wide range of residential amenities, including an underground parking garage for cars and bicycles, a business center, a gym, a yoga studio, a competition-sized pool, a sky lounge and a landscaped rooftop deck.  Interior features will include stainless steel appliances, quartz countertops, high-speed internet and washer-dryer units in each apartment. Designs from Killefer Flammang Architects call for the construction of three contemporary six-story buildings, centered around a pedestrian paseo. Next On Lex, which is billed as the largest multifamily development to break ground in Los Angeles County this year, is part of a $1.3-billion development pipeline for Century West Partners. The company is also in the midst of construction on two similar residential developments in Koreatown.