Changes in land use/cover that are commonly associated with urbanization can dramatically influence the amount, chemical form, and spatial distribution of carbon (C) stocks. Measured values and relative literature for composition of natural and anthropogenic materials have been compiled. These data are used in conjunction with land cover statistics and expert assessment of building design to calculate C stocks associated with 150 years of land use change and development for an area of the Po River Valley, Northern Italy. Using 4 time periods (1853, 1954, 1976, and 2003), we demonstrate that the C stocks within this densely populated area have undergone considerable modification. A 52% increase in population density has been associated with an increase in the proportion of total C stored in anthropogenic stocks from 0.2% to 6%; this has been accompanied by a one order of magnitude increase in the carbon emission per capita per unit area. These changes have also been accompanied by a major shift in stocks from organic to inorganic forms of C.