The lush, colorful extravagance of Altamont is the result of decades of nurturing. A shadowy avenue of beech trees leads to bright lawns and flowers beneath ancient yew trees. Gravel walks weave around a lake, constructed as a famine-relief project. It's arguably at its best in late May, when spectacular displays of bluebells fill the forest floor on slopes overlooking the River Slaney, but it's always beautiful.