u/Hot-Degree-264

My family and I are going to Madrid in a couple of weeks and I was hoping to save us money by using my age/student status to get a reduced museum ticket. I know we will be going to the Reina Sofía and Thyssen-Bornemisza. Can I just bring my school ID (U.S. University), or should I buy the ISIC card? The website just says the card is “recommended”. Also, my brother has a disability, so I think he and my mom should be able to get in for free, if anyone has any info on that too it would be greatly appreciated!!