Jamestown’s newest hotel will formally open for business this week, bringing a new offering from developer Hamister Group and Hilton Hotels Corp. to the Southern Tier city. Located at 150 West 4th St., the new DoubleTree by Hilton features 147 guest rooms, along with the Pearl City Hops Restaurant and Tavern gastropub, a bar, a patio, an indoor saltwater pool, a fitness center and 4,100 square feet of banquet and meeting space. It had its “soft” opening several weeks ago. Built in the 1970s, the hotel had previously been a Holiday Inn and Ramada Inn. Hamister purchased the property in 2013 and completed a $13 million makeover with help from a $2.4 million state Downtown Revitalization Initiative award, as well as a 10-year, $350,000 loan from the city.