The Balmoral bonnet is a traditional Scottish hat that can be worn as part of formal or informal Highland dress. Developed from the earlier blue bonnet, dating to at least the 16th century, it takes the form of a knitted, soft wool cap with a flat crown. It is named after Balmoral Castle, a royal residence in Scotland. It is an alternative to the similar and related (informal) Tam o' Shanter cap and the Glengarry bonnet.