London wasn't mapped well until the early modern era, but for a few stylized drawings, but the time travelers of the Historical Towns Trust have the situation under control. Their detailed atlases of 13th-century and Tudor London dig down to individual dwellings, parish boundaries and walls.
The team have put together two exceptionally detailed maps of the capital. The first, Tudor London, zooms in on the year 1520, showing the city shortly before the Reformation swept away the religious houses. The second map goes back as far as the late 13th century, more than 250 years before the dawn of London cartography.
"It's about the earliest date we can really map the city in detail," explains Professor Vanessa Harding, who contributed to the research and is the Chair of HTT. "From the mid-13th century we have a proliferation of written sources for houses, streets and landmarks; all the parish churches were in place, and most of the religious houses, though the guilds had yet to make their mark physically."
The next step is surely a detailed 3D model, then movies and videogames! There remain, to quote one of the experts involved, many "unknowns and unknown unknowns" when it comes to mapping medieval and early modern London. "We feel particularly cautious about suburban parish boundaries c.1300."
You can buy paper maps here—also those of various other towns—or explore the digital ones online (e.g. medieval London, Tudor London, but there are all sorts of overlays to view)