An Icon Is Preserved
Following two years of planning, testing, and design, the Department of Conservation
and Recreation (DCR) is embarking on a comprehensive rehabilitation of the Plymouth
Rock Portico. DCR apologizes for any inconvenience to the public caused by this
preservation project. However, the work is necessary to ensure many more years of
public enjoyment of both the Portico and Plymouth Rock.
History of the Portico
Plymouth Rock rests on a significant historic site where, tradition tells us, the
passengers on the Mayflower first made a permanent home in North America in 1620.
But the Portico covering Plymouth Rock is itself an historic monument. The Neo-Classical
structure was designed by the highly influential architectural firm of McKim, Mead
and White and built in 1921, replacing an earlier Gothic-style monument. At that
time, many significant buildings across the United States, such as libraries and
government centers, were built in the Neo-Classical style to suggest permanence,
stability, and strength. Almost fifty years later, in 1970, the Plymouth Rock Portico
was listed in the National Register of Historic Places.
What Happened to the Portico?
While the Portico appears to be built from solid granite, it actually contains mortar,
terra cotta tiles, and other materials. These are all reinforced by steel beams
inside the masonry at the dome's edges. Over time, the mortar between the granite
blocks around the top of the Portico has deteriorated. This has allowed water to
seep into the structure and cause the interior steel beams to rust and expand. As
a result, the surrounding mortar and tiles have crumbled and begun to fall, the
exterior of the Portico is being stained by water flowing in and out of the mortar
joints, and other associated structural and cosmetic problems have arisen.
Ongoing Rehabilitation Activities
Repairing past damage and preventing future problems with the Portico are the main
goals of this project. Due to the historic significance of the Portico, DCR is proceeding
with caution, removing as little historic material as possible, and adding as little
modern material as possible. The work you see before you includes cleaning rust
from the internal steel, replacing damaged tiles with custom-made and historically
appropriate copies, cleaning all the granite masonry, replacing failed mortar joints,
and replacing the roof. As an added precaution, DCR is installing a "cathodic protection"
rust-prevention system. This involves connecting a safe, mild electrical current
to the internal steel frame, which halts the chemical process that causes rust.
This method has protected pipelines and ships for many years, but has only recently
been used to protect historic structures in Europe and the United States. The end
result of all this work will be a structurally stable, but visibly unchanged, Plymouth
What do the Portico, Ellis Island, and the Boston Public Library have in common?
The Portico's vaulted, terra cotta tile dome is based on a traditional Spanish method
of building called "Catalan vaulting," which was adopted in the United States at
the turn of the century by the Guastavino Company, a firm based at the time in Woburn,
MA. Their distinctive constructions are found in a number of famous American buildings,
such as the Great Hall at Ellis Island in New York, the Boston Public Library, and
the addition to Pilgrim Hall in Plymouth.
March 24 – June 30, 2008
Portico Closed for Rehabilitation
July 1 – September 28, 2008
Visitors will be able to view Plymouth Rock through a viewing corridor.
October 1, 2008
Portico rehabilitation completed.
Agency: Department of Conservation and Recreation
DCR Contact: Shaun Provencher 617 626-1376
Architects: Bargmann Hendrie + Archetype, (BH+A) Boston, MA
Contractor: Chapman Waterproofing Company Boston, MA