Sewall-Belmont House National Historic Site: This National Historic Site and National Monument served as the headquarters for the National Woman's Party for nearly 90 years.

The Sewall–Belmont House National Historic Site served as the headquarters for the National Woman's Party (NWP) for nearly 90 years, starting in 1929. Originally founded by Alice Paul and Lucy Burns to rally women to support the passage of the Nineteenth Amendment, the NWP remained a major force in organizing women for political action, including for the passage of an Equal Rights Amendment (ERA). This house served as the NWP's headquarters during a critical period for the organization, following its purchase by NWP benefactress and cofounder Alva Vanderbilt Belmont. The organization named their headquarters the Alva Belmont House in her honor. It was also declared the Belmont-Paul Women's Equality National Monument in 2016.

The house was originally built in 1800, incorporating a two-story house from 1750. It burned in 1814 and was rebuilt in 1820. "Sewall" refers to Robert Sewall, the man for whom the house was originally built between 1799 and 1800.

DC Inventory: November 8, 1964 (Joint Committee on Landmarks)

National Register: June 16, 1972

Natonal Register (Additional Documentation): September 5, 2025

National Historic Site: May 30, 1974

National Historic Landmark: May 30, 1974

National Monument: April 12, 2016

Within Capitol Hill Historic District