How to get the geometry type of an empty PostGIS table?

I have a web application that needs to know the geometry type of a PostGIS table's geom field before inserting rows into it. I use the following query to determine the geometry type of the geom column:

SELECT GeometryType(geom) FROM my_schema.building LIMIT 1

This returns the geometry type of an actual row, so it does not work when my table is empty. How do I determine the geometry type of the geometry column itself?

Answer

The query could be run against the geometry_columns table in this way

SELECT type 
FROM geometry_columns 
WHERE f_table_schema = 'my_schema' 
AND f_table_name = 'building' 
and f_geometry_column = 'geom';

(or, if you are using a geography type, subsititute geometry_columns with geography_columns and f_geometry_column with f_geography_column)