A 150-room Marriott Residence Inn has opened at 570 Arsenal St. in Watertown, a project led by Boylston Properties of Boston.

It’s the town’s first new hotel in over a half-century. A ribbon-cutting ceremony was held this week at the site, formerly the Charles River Saab dealership.

Designed by Stantec, the 6-story extended-stay hotel includes 845 square feet of meeting space, a dining room, business center, lounge, pool and fitness center. The pet-friendly property will offer free wired Internet and Wi-Fi service. Stonebridge Cos. of Colorado is the co-owner and manager.

Group One Partners of Boston designed the interior. Watertown-based VHB provided engineering and landscaping design, and Procon of Manchester, New Hampshire was the general contractor.

Boylston Properties’ development activities in East Watertown include the Arsenal Project shopping center and Harvard Vanguard Medical Assoc. building and the LINX office-lab building at 490 Arsenal Way.