diff --git a/pytential/qbx/__init__.py b/pytential/qbx/__init__.py
index d5d52ca6daa575484ae621ded4668179c01f1266..31538d564b43bbbd2805d4a9d3d2c80d0e300108 100644
--- a/pytential/qbx/__init__.py
+++ b/pytential/qbx/__init__.py
@@ -38,12 +38,43 @@ logger = logging.getLogger(__name__)
 
 
 __doc__ = """
+.. autoclass:: GeometryCollection
 .. autoclass:: QBXLayerPotentialSource
 
 .. autoclass:: QBXTargetAssociationFailedException
 """
 
 
+# {{{ GeometryCollection
+
+class GeometryCollection:
+    """
+    .. attribute:: places
+    .. attribute:: refined_places
+    """
+
+    def __init__(self, places):
+        """
+        :arg places: a mapping of symbolic names to
+            :class:`pytential.discretization.Discretization` objects or a subclass
+            of :class:`pytential.discretization.target.TargetBase`.
+        """
+        pass
+
+    def drive_refinement(self, get_refiner):
+        # This needs to construct all sources' QBX centers and refine other
+        # sources for them.
+        pass
+
+    def __getitem__(self, name):
+        pass
+
+    def _tree_for_source(self, name):
+        pass
+
+# }}}
+
+
 # {{{ QBX layer potential source
 
 class _not_provided:  # noqa: N801