President Obama March 25 designated 480 acres on Maryland’s Eastern Shore as a national monument to anti-slavery icon Harriet Tubman, pushing back against congressional critics who said his approach to enshrining the Underground Railroad is an abuse of the federal Antiquities Act.

The Harriet Tubman Underground Railroad National Monument will be a national park; an expansion from the existing state park on Maryland’s Eastern Shore and is to open in 2015.

“By selecting Maryland’s Eastern Shore as the site for the Harriet Tubman Underground Railroad National Monument, President Obama will help us preserve the life and legacy of an American hero,” Gov. Martin O’Malley said in a statement. “Thanks to the hard work and commitment of many, Harriet Tubman’s legacy will live on forever.”

The monument will feature large landscapes designed to represent Tubman’s life as a slave and work with the Underground Railroad. It will also include Stewart’s Canal, a seven-mile canal that was dug by slaves in the early 1800s.

In addition to the Harriet Tubman project, President Obama also designated four additional National Monuments under the Antiquities Act. They are: First State National Monument in Delaware; Charles Young Buffalo Soldiers National Monument in Ohio; Río Grande del Norte National Monument in New Mexico; and San Juan Islands National Monument in Washington State.

“These sites honor the pioneering heroes, spectacular landscapes and rich history that have shaped our extraordinary country,” Obama said. “By designating these national monuments today, we will ensure they will continue to inspire and be enjoyed by generations of Americans to come.”

Congressional Republicans criticized the president for designating five new national monuments at a time when sequester funding cuts are hitting existing national parks and landmarks.

“President Obama has closed the White House to public tours but he’s unilaterally ordering the National Park Service to spend scarce dollars on little-known, privately-owned property in Delaware,” Rep. Doc Hastings (R-Wash.) said in a statement. He is chairman of the House Natural Resources Committee.

Hastings assailed Obama’s use of the 1906 law that allows the president to designate lands for federal protection.

“The Obama administration not only sees the sequester as an opportunity to make automatic spending reductions as painful as possible on the American people, it’s also a good time for the president to dictate under a century-old law that the government spend money it doesn’t have on property it doesn’t even own,” Hastings said.