What is a railway? Well a definition many people will agree with is that a railway is a track system which wheeled vehicles run on, guided by the tracks. The earliest of these tracked systems goes back all the way to the Classical World .
Ancient Greece and later Rome had a number of tracked systems, the most well-known of which being across the Isthmus of Corinth called the Diolkos which was used by the Corinthian Navy from 600BCE to transfer ships  from the Corinthian Gulf to the Saronic. These tracked systems were unlike what we would consider a modern railway though, consisting of deep grooves cut in stone slabs for the wheels of vehicles to travel in. Such grooves have been found in a number of locations across the Classical World, a notable one being at the Três Minas gold mine in Portugal .
One problem with tracing tracked systems of this period is that the passage of time and the lack of supporting evidence means that it is difficult sometimes to know for sure if grooves are the remains of a track system or just the natural wear and tear caused by thousands of carts over the years . However consistent gauge and depth is a good indicator that a tramway once existed at a given location. The gauge usually used by Roman tramways was around 1.2m which isn't far off standard gauge today . The grooves usually cut across the centre of the slabs, which would be remarkable to just be by coincidence.
After the fall of the Roman Empire such tramways fell into disuse or at least their continued use in the so-called Dark Ages has not been documented. Railways began to reappear in Europe during the late Medieval Period, a common type being known as the Leitnagel which used pins on trucks guided by a wooden track. A method similar in manner to a Scalextric!  These railways were generally short in length and usually underground in mines to transport mined materials to the surface. Leitnagel trucks were small in size, around 1.2m long and 1/2m wide (early mines often had narrow tunnels) and were pushed along by miners. The blunt pin running in the groove in the track to stop it from leaving the track. The trucks were known as dogs as when they moved they were said to make a sound like a dog bark! 
It was this type of railway which was introduced to England in the 1560s. Queen Elizabeth set up the Company of Mines Royal in 1564 to mine copper which was needed in ever greater quantities for bronze production for cannons. Surviving inventories from the time list, and physical evidence has been found, of Leitnagel type railways at mines in the Keswick area of Lake District in the late 1560s. These railways are probably the first in England.
|Leitnagel Trucks by Georgius Agricola (De Re Metallica) [Public domain], via Wikimedia Commons|
To be continued...
 Andy Guy & Jim Rees, Early Railways 1569-1830 (Shire Publications, 2016) p. 7
 J. G. Landels, Engineering in the Ancient World (Constable, 2000) p. 183
 Mark Jones, Discovering Britain's First Railways (History Press, 2012) p. 15
 Landels p. 182
 Jones p. 10
 Guy & Rees p. 8
 Georgius Agricola, De Re Metallica Book VI (1561) p. 156
 Bertram Baxter, Stone Blocks & Iron Rails (Tramroads) (David & Charles, 1966) p. 15