Museums, fitness centers, movie theaters, casinos and other businesses will be able to open their doors Monday under the third phase of the state’s four-step process to re-open the economy. Governor Charlie Baker announced today.

Phase 3 will begin everywhere except in the City of Boston, where it will begin on July 13.

“These employers are hugely important to so many people here in Massachusetts,” Baker said. “Thanks to the hard work everyone has put in so far, we’re pleased to say that more places can reopen with strict new guidelines.”

Businesses opening Monday must meet all safety standards, create a COVID-19 control plan, and complete a self-certification.

Also eligible to re-open Monday are professional sports teams, which may operate under the authority of league-wide rules and hold games without spectators.

The state released a four-phased plan in May to reopen the economy based on public health data, spending at least three weeks in each phase. Since mid-April, the seven-day average for the positive COVID-19 test rate is down 94 percent, the three-day average of hospitalized patients is down 79 percent and the number of hospitals in surge is down 86 percent.

The governor has also updated his order on gatherings. Indoor gatherings are limited to eight people per 1,000 square feet but should not exceed 25 people in a single enclosed, indoor space.

Outdoor gatherings in enclosed spaces are limited to 25 percent of a facility’s maximum permitted occupancy, with a maximum of 100 people in a single enclosed outdoor space. This includes community events, civic events, sporting events, concerts, conventions and more. The order does not apply to outdoor, unenclosed gatherings if proper social distancing measures are possible.

Health-care providers may continue to provide in-person procedures and services as allowed in Phase II, with the addition of certain group treatment programs and day programs. These programs include adult day health, day habilitation programs, and substance abuse services day treatment and outpatient services. Certain human services programs can reopen including community-based day services for adults with intellectual and cognitive disabilities and psychosocial rehabilitation clubhouses.