there's an 1869u sds,ge odectic, service map representation that's somewhat accurate, not where lots are provided but there's a little black dot and the whole thing is about 24 inches by 30 inches and covers the whole city. so it's not fine grained but you can say there was blob there in 1869. >> do they have this many the history room? >> yes. if you do a web search you can find it on-line. there's one source where you can actually like zoom in and there's another,us coast map from the 1850s but i would think pretty much any building from the 1850s is already kind of done. >> this gentleman has a question? >> are they consistent block numbers from year to year and agency to agency. >> they have changes. when the original city was layed out by the city surveyor it was called the 50 bar survey. when it was expanded to market. so up until the teens the city kept those as separate surveys and theres the different surveys in the outside lands which is sort of the western part of the city. >> the uninhabitable part of san francisco. >> they were different surveys and blocks in those. miss