Ballinafad Castle is an Elizabethan blockhouse built during the Nine Years' War by Captain John St. Barbe on land granted to him by King James VI and I. The castle was garrisoned by ten men and commanded by John St. Barbe. It was partially destroyed by Red Hugh O’Donnel in 1595. The castle was again sacked in 1642 and fell out of use by 1680.
Today it is in ruins and is accessible year round. There are no tours, guides, or fees. Visitors can park in a small carpark at the foot of the hill where they will find an interpretive sign. Visitors cannot enter the castle, but the interior is visible through breaches in the walls that are closed off by iron fences.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.