The original grand plaza has undergone several extensive renovations, with radical changes in its appearance and utility. Prior to the 1960s there were extensive brick plazas, few trees, and a few large, simple, raised, and circular ponds with central fountains, all in a style that discouraged loitering. The plaza was then extensively excavated for underground parking. At this time a central rectangular pond, with an extensive array of water vents (strangely, all in several strict rows and all pointing east, with identical arcs of water, and completely without sculptural embellishment), was added, with extensive groves of trees (again, in 60s modernist style, planted with absolute military precision on rectangular grids). In the 1990s, with the rise of the problem of homelessness, the plaza was once again remodeled to make it somewhat less habitable—although the most significant change, the replacement of the pond and pumps with a lawn, could be reasonably justified on the basis of energy and water conservation.