That is the oldest subsription library in the world , the second oldest is at Wanlockhead about 2 miles away. The two mining communities are either side of a county boundary with different landowners, that rivalry still exists today.
The libraries were a way of the miners and their families becoming educated , he Mining Museum in Wanlockhead is open during the summer and weekends (you need to check) well worth a visit . It came very close to closure a few years back but was saved by Scottish Government . Both villages are worth a mooch around. The landowner on the Leadhills side is quite happy for you to explore the workings on the hillside not so on the Wanlockside
can also reccomend the Hopetoun Arms Hotel Leadhills, not cheap unless you are camping there is not a lot of places to eat and drink around there
NCRMS (as was) had a visit to the area in spring 1971 or 2 and we had a fine time wandering around various sites, including a stop-off at the Barjarg stone mine (pump then still in situ, pic and info in Archive album), as Mike says well worth the effort, the remains of the flues on the hillside at one smelt mills appear almost lunar in the lack of vegetation. We were given a guided tour around the delights of the library but that's a long time ago. It was also much cheaper as we used the Series One Landrover (see Faggergill Archive, if you're still logged-on to AN) and camped, it was a bit cold, frosty and snowy but I was even more stupid in those days