Plans call for a building on each of the two, city-owned lots that straddle Park Street at its intersection with Main. The units — six studios, 72 one-bedrooms and 30 two-bedrooms would be a mix of market-rate and workforce or so-called “affordable” housing. According to the Capital Region Development Authority, the market-rate rents are now estimated to range from $1,200 to $1,700 a month.