The remains of the Castle can be visited
Bolingbroke Castle

Bolingbroke Castle, a ruined castle in Lincolnshire, England, was built without the central keep common at the time, relying instead on a strong curtain wall and D-shaped towers.
History+
The origins of fortifications at this site date back to the 6th or 7th century, when the Saxons established the first structures here. In the 12th century, a Norman motte-and-bailey castle followed on a nearby hill. The present stone castle was commissioned in 1220 by Ranulf, Earl of Chester, shortly after his return from the Fifth Crusade. Ranulf died childless in 1232, after which the castle passed into the possession of his sisters. Later, in 1361, Bolingbroke Castle came into the ownership of John of Gaunt through marriage. His son Henry, born here in 1367 and later to become King Henry IV of England, was known as “Henry Bolingbroke.” In 1368, John's wife Blanche of Lancaster died of the plague at the castle. During the 15th and 16th centuries, the complex increasingly fell into disrepair. A survey in 1636 found that the towers were beyond repair.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Colin Jackson
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 53.1652, 0.0170