All year I’ve struggled with museum opening times. There are hundreds of museums and galleries across the city, but most close by 5 or 6pm, shutting us workers out. Thankfully I’ve begun to realize that they don’t ignore us entirely, because a handful throw open their doors late one night a week – and entry is free.

Tonight I took advantage of one such late-night opening at the Morgan Library and Museum on Madison Avenue. I didn’t know much about it before I went and I’ve never really noticed the building – so I was stunned to see how massive it was when Ryan and I walked inside.

In 1906, the building, which is between 36th and 37th Streets, started to house the growing library and private art collection of John Pierpoint Morgan – the man behind banking giant, J.P. Morgan. During his lifetime, Morgan dominated corporate finance and industrial companies, and subsequently spent his riches on rare manuscripts, a vast and varied collection of art and lots and lots of books. After his death, his son handed over the library to the public in 1924.

For me, the highlight was his grand library and study room. The library was just breathtaking. He had amassed 10,000 books by the time he died, and they lined the walls of this vast room – each beautifully covered with leather or patterned materials.

There were also some really impressive collectors items among them – including a copy of the Gutenberg Bible, the first ever text to use movable type (he actually had two-and-a-half copies, which is ridiculous considering there are only 48 in existence), as well as original scores by Verdi and Beethoven, among others.

The Beethoven was on show in his study room, which had high decorative ceilings, maroon covered walls and a grand fireplace. At one end of the room was a dominating desk and at the other end, there was a vault – but rather than filled with gold, it was lined with some of the more expensive texts in his collection.

I loved this study room because it was just inches from the streets of Manhattan and yet I felt like I was miles away from the city. It was like an old-fashioned (very luxurious) man cave and I loved the idea of Morgan sweeping into this room after a day down at Wall Street to engross himself in his projects and separate himself from the city.

In another small library room in this wing, there were some great artefacts from his collection. Ryan and I particularly loved the tiny beads that had been inscribed so that when they were rolled over clay, they would make a continuous pattern. They were from Mesopotamia – so thousands of years B.C. – and the quality and precision was just unbelievable.

As well as housing Morgan’s collections, the museum hosts the work of other artists or writers in newer sections of the building. Right now, it has exhibitions of Edgar Allen Poe, Leonardo Da Vinci and Giambattista and Domenico Tiepolo. The latter was my favourite, although I didn’t know their work beforehand. They used ink pens to create beautiful, atmospheric pieces that looked so modern – rather than hundreds of years old.

I also learned that Da Vinci wrote in mirror script (that is, from right to left, from the back of the book to the front) throughout his life. Did you know that? I couldn’t get my head around it, but I did think it was kinda cool.

This is a beautiful building and has some really fascinating artefacts inside, and yet I don’t think it’s one that tourists (or residents) would necessarily know about. But for people like me, who are attached to an office desk every day until after museum close, it’s great that it’s open late. The one problem with this free offering is that it can get kind of busy, so I’d suggest getting there for 7 on the dot and making a beeline for that gorgeous library room.

For more other late-night openings, check out Time Out New York’s list here.