Listed buildings in Lancaster, Lancashire century. The town stands at the lowest crossing of the River Lune, and received its first borough charter in 1193. In addition to being a market town, it became the judicial centre of the county of Lancashire, the castle being converted to serve this purpose in the 18th century. Also in the 18th century, in order to trade with the Americas, St George's Quay, with its warehouses and houses, was developed. Towards the end of that century the Lancaster Canal was built, linking the town with Preston. And in the 19th century railways came to the town, including what is
Spherical lune two polar opposite points. Common examples of great circles are lines of longitude ("meridians") on a sphere, which meet at the north and south poles. A spherical lune has two planes of symmetry. It can be bisected into two lunes of half the angle, or it can be bisected by an equatorial line into two right spherical triangles. The surface area of a spherical lune is 2θ "R", where "R" is the radius of the sphere and θ is the dihedral angle in radians between the two half great circles. When this angle equals 2π radians (360°) — i.e., when