Most listings are in the $10's per square foot per year. The Cambridge region is going through a a boost in rates. In the last 3 months, the median rate went up $18 per sqft per year.
In the last 90 days, 0 listings have been posted online, which means spaces most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About Inf% of the listings in the Cambridge are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
Even though the median size is 3,700 sqft, there are still 0 office spaces below 2,000 sqft. Most properties in this area are close to 1 floors. Most buildings in this area were built in 1951 and are Class A.