Great Road linking Arnor and Gondor, running from Fornost in the North to MinasTirith in the South, a distance of well over 1000 miles. It crossed the Great East Road at Bree and the River Greyflood at Tharbad, running S-SE through Enedwaith and Dunland to the Fords of Isen. Passing the Gap of Rohan, it ran E-SE through the lands of the Rohirrim, skirting the WhiteMountains, and entering Gondor at the crossing of the MeringStream.
The Road was a testament to the might of the Dúnedain at the beginning of the ThirdAge, and for many years facilitated trade between the North and South Kingdoms (it is not recorded if the Road existed before then). The Road therefore came to embody the relative fortunes of the two realms throughout the ThirdAge: with the partition of Arnor and the withdrawal of Gondor from Enedwaith, much of the Road North and West of the Gap of Rohan had probably already fallen into disrepair. It was via the Road that the Great Plague of 1636 was able to spread into the North. After the fall of Arnor at the hands of the Witch-king, most travellers (except the Rangers) avoided the dilapidated stretch of highway between Tharbad and Deadmen's Dike (as Fornost came to be known), and this became known as the Greenway. Until the end of the ThirdAge, traffic along the Road between Rohan and Eriador was largely conducted in secret (it became a trading route once again - of sorts - between Isengard and the Southfarthing just prior to the War of the Ring).
East of the Gap of Rohan, the Road was maintained by the Dunedain and (later) the Rohirrim, and from 2510 it came to symbolise the great alliance between Gondor and Rohan. In the War of the Ring it sped the host of Théoden to the Battle of the Pelennor Fields, although they were obliged to detour along a disused track through the Stonewain Valley in order to circumvent an army of Orcs and Southrons that waylaid the Road North of the Druadan Forest.
In the FourthAge the Road doubtless became an important route once again between the North and the South of the ReunitedKingdom.