Journal of Architectural and Planning Research 9:4 (Winter, 1992) 317 ments had been legislatively abolished in 1782. Yet ninety-nine year leaseholds likewise became the customary tenure form for building lots (Mayer, 1883: 49-51). Baltimore ground rents served another economic function. They made land more marketable by providing liberal financing terms. For example, in 1769 Ann Fell leased land to Alexander McMechen for ninety-nine years, renewable forever, at an annual rent of 10 pounds, 10 shillings. No down payment was required; the vendor had enhanced the salability of her land by lending the purchase price (Myers v. Silljacks, 1882: 330). The ground rent system also served the land speculator. McMechen immediately subdivided his leasehold into three parts and assigned two lots to sublessees who agreed to pay the entire annual rent of 10 pounds, 10 shillings; he kept the third lot, exonerated from rent obligation, as his profit. In taking his profit McMechen had not been required to invest any capital. HOUSES FIGURE 1. Section from Bradford's Map of Birmingham °ncs;the land in Birmingham was freed for 1750. Source: C.W. Chalkin, The provincial towns of Georgian development, Construction proceeded England. rapidly. During the late eighteenth century over ten thousand dwellings were erected in and around the city center. Increases in the value of land promoted "in- filling" in the gar- dens behind the grand houses and "polite terraces" left over from earlier decades. Most of the new dwellings were for impoverished workers and consisted of only two or three rooms (Chalklin, 1974: 107-108,196-197). Slum housing came in a variety of configurations designed to increase the density of habitation. Houses were "jerry-built" back-to-back, at right angle to the street. Tunnels through the ter- raced houses afforded access to the resulting courts (Muthesius, 1982: 107-108; Chalklin, 1974: 66-72). The turn of the nineteenth century also witnessed an unprecedented growth in Baltimore's low income housing stock. Its masses lived very much as their Birmingham brethren did. In the low-lying districts surrounding the waterfront, houses in block rows bordered the main streets. Behind them shanties and sheds were connected by alleys and court yards. Just as in Birmin- gham, these warrens were the product of exigency rather than design. Profit-maximizing