I would begin my search by focusing on specific scholars I would want to work with. After you write down such a list, see if there's a geography department where several such scholars from your list are employed. Once you've done so, you can send an email to the Head of that department asking about the process required for becoming a visiting scholar there.
There are at least three approaches to a good choice, both of which can be undertaken in unison. First, identify universities which have departments of geography and/or urban planning and which also offer graduate programs in these fields, especially Ph.D.s. Second, seek information sources on which programs are seeking faculty to fill temporary positions, although these requests often are not announced until later in the year. Third, identify leading scholars in your area of interest or POTENTIAL interest and determine their affiliations.
Universities that comply with two or all three of these criteria should prove quite attractive.