We have our young "London" grandchildren here for a few days. "We always spend Halloween at Granny's". Hide and seek in the dark, pumpkins, blind man's buff, cooking, Halloween hats etc. These days it has become very commercialised sadly, but we will do our best to give them a good time. My health is not as good as it could be.
Halloween is the eve of All Hallows Day (All Saints Day). Some believe the celebration of Halloween dates back to Pagan times.
See https://en.wikipedia.org/wiki/Halloween .