2021 US MNH Priority Mail Castillo De San Marcos Mail Pane of 4 Stamps

Value:  $7.95 Priority Mail Rate

Issue Date:  January 24, 2021

First Day City:  St. Augustine, FL

Type of Stamp:  Definitive

Printed by:  Ashton Potter (USA) Ltd.

Printing Method:  Offset, microprint

Format:  Pane of 4

Self-Adhesive

Quantity Printed:  5,500,000

The Castillo de San Marcos (St. Mark's Castle) is the continental United States' oldest masonry fort.  It was designed by Spanish engineer Ignacio Daza and built on the western side of Matanzas Bay in St. Augustine, Florida.

The Castillo de San Marcos was originally a Spanish fort, but came under British control in 1763.  It was returned to Spain in 1783 before it was ceded to the United States in 1821 under the Adams-Onis Treaty.  At that time, the US renamed the structure Fort Marion and turned it into an army base.  The fort was declared a national monument in 1924.  After over 250 years of military service, the site was deactivated in 1933.  In 1942, it was officially renamed Castillo de San Marcos.

Since being declared a national monument and being placed under the administration of the National parks Service, the Castillo de San Marcos has become quite popular with the public.  it is known for its masonry star shape and unusual coquina walls made of countless tiny shells held together by a special type of mineral.  This unique building material was taken from the "King's Quarry" on Anastasia Island across the bay from the Castillo.

It took 23 years to build the Castillo de San Marcos, and it has stood for over 325 years.  It has become an enduring symbol of Spain's part in US history.