MySQL database for storing city bounding boxes and names I need to design a mysql database which contains a table of cities which supports only a single query - given a point, return the city (or cities) which it falls in. I have the bounding box for each city. What should the column look like to store the city bounding box to fully take advantage of mysql's spatial-indexing, multiple POINT columns? POLYGON? And what does the query look like.

Most discussion I've seen of spatial indexing involves the inverse question - given a bounding box, return the set of entries which have a POINT column which falls within the bounding box, which they are able to do using MBRWITHIN to obtain.
(Not a full answer, but too long for a Comment.)

With 200 cities with 'retangular' bounding boxes, virtually anything will do.  Even a simple table without a SPATIAL index, but with INDEX(latitude), INDEX(longitude).

3 million cities, on the other hand, needs some serious indexing.  SPATIAL, as you are asking about, is probably the 'right' way to do it.

Here is an efficient way to do it without SPATIAL, using PARTITIONing and special code instead.  (However, the code given is aimed at a different problem, so it is not directly applicable.)