The Palestine Exploration Fund is a British society based in London. It was founded in 1865, shortly after the completion of the Ordnance Survey of Jerusalem by Royal Engineers of the War Department. The Fund is the oldest known organization in the world created specifically for the study of the Levant region, also known as Palestine. Often simply known as the PEF, its initial objective was to carry out surveys of the topography and ethnography of Ottoman Palestine – producing the PEF Survey of Palestine. Its remit was considered to fall between an expeditionary survey and military intelligence gathering. There was also strong religious interest from Christians; William Thomson, Archbishop of York, was the first President of the PEF.

The Ordnance Survey of Jerusalem of 1864–65 was the first scientific mapping of Jerusalem, and the first Ordnance Survey to take place outside the United Kingdom. It was undertaken by Charles William Wilson, a 28-year-old officer in the Royal Engineers corps of the British Army, under the authority of Sir Henry James, as Superintendent of the Ordnance Survey, and with the sanction of George Robinson, 1st Marquess of Ripon as Secretary of State for War. The team of six Royal Engineers began their work on 3 October 1864. The work was completed on 16 June 1865, and the report was published on 29 March 1866.