Hello May
I think in the extract which you quote, the present simple is used to describe Paris because, for the author, the statements are fact. It's a bit like saying, 'Paris is in France' or 'I love chocolate'. For this author, it's 'a place that I love' and 'the light is different' etc. In other words, these things are generally true, so the present simple is used.
The past tense is used when he/she is recalling a particular visit to Paris which happend some time ago and is now over, so a variety of past tenses is appropriate.
Continuing the chocolate theme, consider this:
I adore chocolate. Of course the Swiss make better chocolate than the Belgians. The last time I was in Geneva, I was sitting in a little cafe where they make award-winning chocolate cakes. No-one knows the secret ingredient. It had been some time since I had eaten, so I ordered a large portion and it was simply delicious. I'd love to go back there again one day. Will you come with me?There's a mixture of verb tenses in that but it makes perfect sense, doesn't it? OK, it won't win me any literary honours, but I hope it helps clear up any confusion. English verbs are the worst part of learning the language for the majority of foreign students - at least that was the case in my teaching days.
Follow your bliss