The crest of the city of Valencia is very interesting.  It has been the crest of the city since 1377.  In that year King Jaime I gave Valencia this crest.  The  reason the bat is on top is unknown.   The crown is because of the royal connection.  The two letter "L" was to show that Valencia was twice loyal to him.   During much of Spain's early history (up to the time of King Ferdinand and Queen Isabella) there might be two or three kings ruling different parts of Spain at the same time.  These kings would try to get cities to be on their side and to wage war against other kingdoms.  During the reign of King Jaime I, Valencia twice remained on his side during wars against other kingdoms.   This was so important to him that he allowed Valencia to put this on their official city crest.