Missing clamps using for connections

Sightseeing Grodziec castle we can find stone elements which were connected by clamps. Are there more such examples? Clamps are characteristic examples of stone blocks connections in ancient buildings in many places in the world.

Can also be found such a stone elements, which are not fitted to others, therefore there were placed together (little out of the way).

See also: Zamek Borkowo – tajemnicze bloki