The meandering line that divides the island of Ireland is one of the main reasons why the UK's exit from the European Union has been so fraught.
The 310-mile international border between the Republic of Ireland and Northern Ireland weaves across an almost entirely rural landscape, following rivers and streams, cutting through farms, lakes and rail tracks.
Snaking from Lough Foyle in the north to Carlingford Lough in the east, the border represents centuries of conflict. A partition created in 1921, it led to decades of war and death.
After Brexit, this boundary will be the only land border between the United Kingdom and the European Union. That could lead to Northern Ireland and the Republic of Ireland having different customs arrangements.
If the UK leaves the EU without a deal it could lead to a return to border posts, creating a so-called “hard border.”
There are 208 border crossings. Some are highways, some a maze of country lanes, some are privately owned on one side and publicly maintained on the other. Some roads even cross the border multiple times.
In Middletown, County Armagh, the border zig-zags across a section of a village road. A right turn at the crossroads takes you into the Republic, while the road to the left, Northern Ireland.
110 million people travel across the border annually and 72 million vehicles traverse it each year, some 6.7 million of these carrying commercial goods.
Agriculture is a major part of Northern Ireland’s economy and most farms are family or mid-sized businesses located near the border, which they trade across.
During the period of violence between nationalists seeking a united Ireland and loyalists wishing to remain a part of the UK, most border roads were closed, making everyday life difficult. Cars would queue at customs, army or police checkpoints, while farmland and barns were used for hiding weapons and people.
The complex issue of the Irish backstop, part of the UK’s withdrawal deal from the EU, put the intricacies of the border back into the headlines, placing a spotlight on places like Jonesborough, County Armagh, for example, where the village church is in Northern Ireland, its graveyard in the Republic.
There are concerns over how Brexit will affect the 1998 Good Friday Agreement (or Belfast Agreement) which helped bring an end to decades of conflict. Those who live near the border have been through much, but fears remain about the impact a hard border could have on the stability of Northern Ireland.