def wikipedia_categories(list_of_pages):
    """
    Find categories of Wikipedia pages.

    @param list_of_pages: List of pages.
    @return: List of categories for each page and the unique list of categories.

    >>> title = 'Kategori:Byggnader_i_Söderort'
    >>> list_of_pages = get_wikipedia_pages_by_category(title, 2)
    >>> wikipedia_categories(list_of_pages)[1][2]
    'Kategori:Ljusskyltar i Stockholm'
    """

    categories = [d['title'] for page in list_of_pages for d in page['categories']]

    return categories, list(set(categories))