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International Day of Monuments & Sites

International Day of Monuments and Sites is celebrated annually all over the world on April 18th as a way to honor heritage, diversity, community, and the environment. 

GPA works tirelessly to promote Philadelphia’s staggering 67 National Historic Landmarks by creating an easily accessible map for tourism and heritage interests. GPA has formed a community within the city’s 67 National Historic Landmarks, offering members, city residents, and tourists alike to learn about cultural heritage and all of the hidden gems of our World Heritage City.

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A community has taken root within the network of the 67 NHLs, with Global Philadelphia there to organize events, tours, SDG partnerships, and educational opportunities in our Learn Philly Heritage program. IDMS is a day for all of these NHLs to come together and acculturate the Philadelphia community. 

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Sign up for IDMS 2026

We invite members of Philadelphia’s NHL community to participate, explore, and share in the city’s rich history. Join us in celebrating these remarkable sites, connect with fellow preservation leaders, and help highlight the hidden gems that make our World Heritage City extraordinary.

Sign up to participate

2026 Featured Sites

 

  • Athenaeum of Philadelphia

  • Arch Street Meeting House 

  • Church of the Advocate

  • Eastern State Penitentiary

  • Founder's Hall at Girard College

  • Historic RittenhouseTown 

  • Independence Seaport Museum

  • Laurel Hill

  • New Sweden Centre

  • Reading Terminal Market

  • Stenton Museum

  • The Hill-Physick House 

  • The Tanner House

 

Full list of phl national historic landmarks

Events & Tours 2026

Global Philadelphia's goal with this day-long series of events is to raise awareness and civic pride in our historic city of Philadelphia. 
 

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Event
Dinah Day with Stenton Museum
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Moravian Bethlehem - PA World Heritage Site

GPA is thrilled to announce that Moravian Bethlehem — one of Pennsylvania's UNESCO World Heritage Sites — will participate in IDMS 2026. As Philadelphia and the nation celebrate the 250th anniversary of independence, Bethlehem opens its doors to bring 18th-century history to life in a way that is immersive, family-friendly, and deeply rooted in community.

World Heritage Tour | Historic Bethlehem Museums & Sites
Learn more
andrea mitchell

Philadelphia Histories Month: A Month-Long Celebration of History Debuts This April

Philadelphia, one of America’s most historic cities, is launching its first-ever Philadelphia Histories Month this April, celebrating the people and moments that shaped its legacy through events, tours, and exhibitions across the city. In addition to IDMS on the 18th, cultural institutions and sites are teaming up to offer special programs at landmark sites and museums, giving visitors plenty of ways to explore the city’s rich history throughout April and May.

Photo courtesy Museum of the American Revolution

Learn more
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What is IDMS?

The aim of the International Day for Monuments and Sites is to encourage local communities and individuals throughout the world to consider the importance of cultural heritage to their lives, identities and communities, and to promote awareness of its diversity and vulnerability and the efforts required to protect and conserve it.

Learn more
Full list of NHLs in Philadelphia

National Historic Landmark Advisory Board

These civic leaders with expertise in history preservation and the NHL landscape aid GPA in preserving, enhancing, and promoting Philadelphia's 67 NHLs.

 

  • David Brownlee, Ph.D., FSAH
  • Michael Norris, Executive Director of Carpenters' Hall
  • Rev. Carolyn C. Cavaness, Pastor of Mother Bethel AME Church
  • Cassie Thomson, Senior Director of Government and Civic Affairs of Visit Philly
  • Paul Steinke, Executive Director, Preservation Alliance of Greater Philadelphia
  • Cornelia Swinson, Executive Director of Historic Johnson House