The Fra Mauro Map, "considered the greatest memorial of medieval cartography" according to Roberto Almagià is a map made between 1457 and 1459 by the Venetian monk Fra Mauro. It is a circular planisphere drawn on parchment and set in a wooden frame, about two meters in diameter.
The original world map was made by Fra Mauro and his assistant Andrea Bianco, a sailor-cartographer, under a commission by king Alfonso V of Portugal. The map was completed on April 24, 1459, and sent to Portugal, but did not survive to the present day. Fra Mauro died the next year while he was making a copy of the map for the Signiory of Venice, and the copy was completed by Andrea Bianco.
The map was discovered in the monastery of San Michel in Isola, Murano, where the Camaldolese cartographer had his studio, and is now located in a stairway in the Biblioteca Nazionale Marciana in Venice, but is visible by entering in the Museo Correr, where it is accessible from the easternmost room upon request to the museum attendants there. A critical edition of the map was published by Piero Falchetta in 2006.

World map
The description of Africa is surprisingly accurate, especially in light of the fact that Portuguese explorers had not yet been beyond 12 degrees North at that date.
Fra Mauro puts the following inscription by the southern tip of Africa, which he names the "Cape of Diab", describing the exploration by a ship from the East around 1420:
"About the year of Our Lord 1420 a ship, what is called an Asian junk (lit. "Zoncho de India"), on a crossing of the Sea of India towards the "Isle of Men and Women", was diverted beyond the "Cape of Diab" (Shown as the Cape of Good Hope on the map), through the "Green Isles" (lit. "isole uerde", Cabo Verde Islands), out into the "Sea of Darkness" (Atlantic Ocean) on a way west and southwest. Nothing but air and water was seen for 40 days and by their reckoning they ran 2,000 miles and fortune deserted them. When the stress of the weather had subsided they made the return to the said "Cape of Diab" in 70 days and drawing near to the shore to supply their wants the sailors saw the egg of a bird called roc, which egg is as big as an amphora." (Text from Fra Mauro map, 10-A13.)
Some of the islands named in the area of the southern tip of Africa bear Arabian and Indian names: Negila ("celebration" in Arabic), or Mangula ("fortunate" in Sanskrit.).
If the account of the roc's egg is not merely a traveler's fable, it would probably have been the egg of Aepyornis, an enormous flightless bird which still existed in Madagascar or had recently become extinct.
Fra Mauro also comments that the account of this expedition, together with the relation by Strabo of the travels of Eudoxus of Cyzicus from Arabia to Gibraltar through the southern Ocean in Antiquity, led him to believe that the Indian Ocean was not a closed sea and that Africa could be circumnavigated by her southern end (Text from Fra Mauro map, 11,G2). This knowledge, together with the map depiction of the African continent, probably encouraged the Portuguese to intensify their effort to round the tip of Africa.

Africa
The Fra Mauro map is one of the first Western maps to represent the islands of Japan (possibly after the De Virga world map). A part of Japan, probably Kyūshū, appears below the island of Java, with the legend "Isola de Cimpagu" (a mis-spelling of Cipangu).

Japan
An even earlier map, the De Virga world map (1411-1415) also depicts the old world in a way broadly similar to the Fra Mauro map, and may have contributed to it.
Fra Mauro also probably relied on Arab sources. This is suggested by the North-South inversion of the map, an Arab tradition examplified by the 12th century maps of Muhammad al-Idrisi, and the detailed information on the southeastern coast of Africa, which was brought by an Ethiopian embassy to Rome in the 1430s.
The map may also have drawn on Chinese sources as described by Ramusio, a contemporary who states that Fra Mauro's map is an improved copy of the one brought from Cathay by Marco Polo:
"That fine illuminated world map on parchment, which can still be seen in a large cabinet alongside the choir of their monastery (The Calmoldese monastery of Santo Michele on Murano) was by one of the brothers of the monastery, who took great delight in the study of cosmography, diligently drawn and copied from a most beautiful and very old nautical map and a world map that had been brought from Cathay by the most honourable Messer Marco Polo and his father." Ramusio v.3.
The Fra Mauro map displays many similarities to the Kangnido map, made in 1402 in Korea, which is based on earlier, now lost, Chinese maps. They share the same understanding of the Old World in its general structure, although the relative proportions of the countries and continents are inverted, with Europe and Africa enlarged on the Fra Mauro map, and China and especially Korea very largely represented in the Kangnido.
These maps were made before the European voyages of exploration and the rounding of the Cape of Good Hope in 1488 by the Europeans. It has been suggested that the geographical knowledge contained in the Kangnido map was created by Muslim, Indian or Chinese sailors (expedition of the Chinese Admiral Zheng He), and then transmitted to the West in some other way, possibly through Indian or Muslim merchants, or through 15th century travelers to the East such as the Venetian Niccolò da Conti.
Fra Mauro and his map were recently celebrated in James Cowan's novel The Mapmaker's Dream.

Notes

"Fra Mauro's World Map", Piero Falchetta, Brepols 2006, ISBN 2503517269