This was a popular showcave on the 19th Century tourist itinerary. I don't know why it closed (for paying guided tours, anyway – it's still fully accessible, for free), but the only visible remnant is a stone step at the entrance.
J.M.W. Turner sketched here in 1816, and it's thought that the 'Fairy Cave' in Emily Brontë's 'Wuthering Heights' is a reference to Yordas Cave. In 1822, Thomas Langdale described this view as "the gateway of some ancient castle".

Beyond the entrance, the cave opens into a huge chamber, ~50 m long by ~15 m wide and ~15 m high. Victorian guides carried candles and burning torches, but even modern headtorches struggle to illuminate more than details and an impression of huge space. Yordas Gill (Old Norse 'jord ass': 'earth stream') flows through the hall; following it upstream one can enter narrower caves featuring flowstone formations (stalactites/stalagmites) and a ~9 m waterfall.
Unfortunately, I was only carrying a bike light with a failing battery, so went no further than the main hall, and barely saw that. Maybe next time.