Hilton San Francisco Union Square this week began a $25 million refurbishment of 575 rooms and suites.
The work is the second phase of a project that began in 2012 with the renovation of rooms, suites and meeting space in the property's Tower 3.
The latest refurb, in Tower 1, will add 37 guestrooms to the hotel, bringing its total number of rooms to 1,919 when it completes in April 2015.
The new rooms will feature a minimalist, contemporary design with dark woods and cool, ocean-inspired colors that "reflect the air of the city by the Bay". Enhancements will include the installation of new entry doors and sound-proofing wall insulation.
Michael Dunne, general manager of the hotel, said: "The first phase of room renovations received exceptional feedback from our guests and we are excited to continue to improve our accommodations with the launch of the enhancement project in Tower 1.
"Our diverse clientele, including business travellers and leisure travellers will enjoy the added comfort and amenities that these modernised rooms will offer."
The final phase of the renovation is planned for 2016 and will include renovations of 350 sleeping rooms and suites in Tower 2.
Hilton's HHonors loyalty programme this week announced a Weekend Rewards promotion to run between February 1 and April 30 (see news, January 23).