The world famous Dumiriya Knot in Demodara

The "world famous Dumiriya Knot" referring to is the Demodara Loop located near the Demodara railway station in Sri Lanka.

It's not a knot in the traditional sense of something tied, but rather a remarkable feat of railway engineering. Here's why it's famous:
Unique Design: Due to the steep incline of the terrain, engineers had to devise an ingenious way for the railway line to gain elevation to reach Badulla. The solution was to create a spiral loop where the track curves around a mountain, passes through a tunnel directly beneath the Demodara railway station, and emerges at a higher elevation.
Station Above Tunnel: This makes the Demodara railway station quite unique, as it is situated directly above the tunnel through which the train has just passed. It's said to be the only loop in the world with a railway station located precisely over a spiral loop tunnel.
Engineering Marvel: Built during the British colonial era (the Badulla extension was completed in 1924), the Demodara Loop is considered a significant achievement in railway construction, especially given the technology available at the time
Folk Tale of Inspiration: Local folklore suggests that the inspiration for the loop's design came from observing a tea estate supervisor untying and re-tying his turban.
Scenic Location: The loop is located in the picturesque hill country of Sri Lanka, surrounded by lush tea plantations, making it a visually stunning area.
So, while it's not a literal knot, the Demodara Loop is a world-renowned and fascinating example of railway engineering that allows trains to navigate the challenging terrain of the region. It's a popular attraction for tourists visiting the area, often combined with a visit to the nearby Nine Arch Bridge.