VIDEO: Mysterious Celtic cross discovered in Donegal forest: https://t.co/qyoWkLJ7SM pic.twitter.com/PtUQrSWSOO — UTV Live News (@UTVNews) October 24, 2016

Flying over Ireland is always a magical experience. But over the past few weeks, travelers speeding over County Donegal have been treated to a particularly mystical sight: a 300-foot-long Celtic cross, made of thousands of trees.

Passengers have been curious about the massive emblem, posting pictures and questions to social media. As UTV Northern Ireland revealed in a short video posted today, the man apparently responsible was Liam Emmery, a forester from the region. Emmery died in 2010, at age 51, after an accident left him unwell for two years. “Even his family knew little about his creation,” which Emmery accomplished by planting different types of trees years ago, says UTV.

The effect has been visible for a few years now, but this year’s dry autumn has made it particularly eye-catching, the yellow cross vivid against a background of spruce green. “We’re going to be appreciating this for the next sixty or seventy years,” horticulturist Gareth Austin told UTV. Not a bad way to go out.