We arrived in the late arvo so not very busy which was good! 5 euro to enter but if you buy a book you get a discount. Very cool library! Definitely felt like I was in Harry Potter. Much smaller than you imagine though. Small selection of English books. Doesn’t take long to see it.
Best Portuguese tarts right next door!! We used the hop on hop off bus to get there (though it stops on other side of the park so you have to walk there).