Interesting art BUT a very strange young man (~24) followed us around. At first we thought he might just be a guard (though he wasn't acting or wearing anything remotely like one). After he appeared completely uninterested in the art and just kept watching us, we became more suspicious and looked directly at him. He then literally tried to hide behind a pillar. This was pretty nerve-wracking because there's only one guard outside all of the exhibitions and it didn't look like there were cameras around, so it definitely felt a bit unsafe (though I am of athletic build, who knows whether they have a weapon or whether they're of a sound state of mind - guessing no to the latter part!). He then left when another lady arrived and we thought that was the end of it.

However, when we left in the direction of the plaza principal, he again continued following us. I immediately stopped dead to see what he would do - he then awkwardly avoided us and continued ahead then sat around the corner in front of the cathedral, glancing our way every so often. There weren't any police around so we just waited there for a bit to see if one would turn up. After ~5 minutes, we still couldn't see one so when a tour bus came, we just decided to jump on it. The bus took a couple of minutes to load up, during which time he just waited and it looked like he was trying to figure out if we were still on the bus/where. I took a couple of photos of him (attached). When we left, he head in the direction of the gallery again.

The entire event was very strange and I'm really not sure what to do about it. There is absolutely no doubt that he was watching and following us. I know the museum takes a record of IDs when entering so if you are from the museum, I would implore you to check who entered alone today (17th June 2021) between 3:30pm and 3:45pm (we think he probably left ~3:45-3:50). As I said, he literally took no interest in the art and who's to know what might have happened if we hadn't spotted him and made our getaway. If anyone else has any advice, please let us know. We don't really want to waste the police's time with it now as it could be he just has some mental issues, though the behaviour was very much off and the art gallery should really be aware of this and take measures against this happening in future.