Cambridge, MA Urban Spaces is underway with its newest development, 121 First St., in Kendall Sq. The speculative 62,100 s/f, $20 million mixed-use development is being built by Needham-based Nauset Construction. The building will feature 48,500 s/f of class A office space and 10,000 s/f of retail space in one of the nation’s hottest real estate markets. JLL is the exclusive leasing agent for Urban Spaces. A summer 2018 completion is anticipated…..