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human
[Harry Potter] If Muggles cannot "see" Hogwarts as it appears like an empty ruin to them, how would muggle born Witches/Wizards' parents come to visit?

Correct me if I'm wrong, but somewhere it is said that since muggles aren't able to see things like magical places, hogwarts school looks like rubble or ruins to them. 

Now, the only known visit by a parent in the novels was Lucious Malfoy and Cederic's father (I think). However, I do realize Lucious was usually only there for his own work/scheming interests. Mr. diggory came to support his son in the tri-wizard tournaments. 

But what if a muggle parent wanted or needed to come to the castle? Say a muggleborn was chosen for Tri-Wizard glory, or the child was in bad shape at the hospital wing. How would a muggle as a parent of a witch or wizard come and navigate in the castle? 

[A friend says parental visitation must be a discouraged notion, but even in the 90's these are not the days parents sent their 5th graders away for 4 months at a time. I know many boarding schools are easily a place for the rich to be rid of their children, but since not attending a boarding school means your child won't learn magic it isn't an option to not send them away. 11-year-olds (even some at 17) have a hard time with being away at camp for a week let alone a year. Imagine the homesickness of a muggleborn family who learned their child would be sent away this long mere weeks before. There are bound to be many reasons a parent might need to come to the castle.]
gpt
Close Muggle relatives of Wizard are allowed by the Ministry to have the Wizarding world revealed to them, in which case they have a spell put on them to become immune to usual Muggle repelling effects. Case in point: Hermione's parents went to Diagonal Alley, which is hidden in the middle of London under a Muggle repelling charm.