Grennan Castle, located near Thomastown, Leinster, Ireland, is a historic site offering a glimpse into the region's rich past. It's advisable to check for accessibility information in advance, as historic sites may have limited access for those with mobility concerns. Whether to explore solo or with a guided tour depends on your preference; guided tours provide more in-depth historical context. Check for any seasonal restrictions or closures before visiting. The cost to visit is generally low, as it is a publicly accessible ruin. A typical visit duration is approximately 1-2 hours, allowing time to explore the castle ruins and surrounding area. Consider wearing comfortable shoes, as the terrain may be uneven.