On the Bristol mapping portal, find out the name of the earliest historical map available in the 'Historic basemaps' section. Additionally, identify the three local authorities that border Bristol, as listed in the map legend. State the name of the oldest map and the three neighboring authorities.
Navigate to maps.bristol.gov.uk. Click on 'Browse historic basemaps' to display the list of historical maps. Identify the map with the earliest date from the expanded list. Click on the 'Legend' link. Locate the 'Neighbouring authorities' section within the legend. Extract the names of the three neighbouring authorities listed. State the name of the oldest map and the three neighbouring authorities.
The oldest map identified is '1750 Rocque'. The three neighbouring authorities listed are 'Bath and North East Somerset', 'North Somerset', and 'South Gloucestershire'.