A developer on Friday will begin construction of a 21-story apartment tower at Pier 4, kicking off a multi-year effort to remake one of the last prime pieces of real estate on the South Boston Waterfront.

Hanover Co. of Houston will construct 369 apartments, retail space, and underground parking at the beginning of the pier on Northern Avenue, the company’s first major project in Boston. Future phases will bring a condominium building, offices or a hotel, restaurants, and a public park at the tip of the pier.