DOES ANYONE KNOW THIS BOOK?

Hey trying to remember the title of a book from when I was younger! The time I owned it was maybe around 2000 or in there somewhere, and I remember the pictures more than the words. Something about a young boy finds a cat, and follows it around town for a while or something. I remember they go past a fountain and into some sort of building (museum possibly?) Anyways at the end he finds a lost poster for the cat stapled to a pole, and it says there's a reward. The little boy takes the cat back home and the reward is one of the cat's kittens, so he picks out a little grey one with blue eyes and takes it home. Thats all I remember. If anyone knows what this book is called please let me know! It's been bothering me!!