The Westerly Armory on Railroad Avenue.

The Providence Journal / Andrew Dickerman

Visit the past. Take a 24-stop tour. Admission’s free.

On Saturday, noon to 3 p.m., as part of National Preservation Month, the Preserve Rhode Island organization presents “Thresholds…Step Inside History,” an open house of two dozen historic sites around the state. You probably won’t be able to get to all the sites, but you can try. For more information, go to www.preserveri.org.

BLACKSTONE VALLEY:

•Captain Wilbur Kelly House, Lower River Road, Lincoln.

•Hannaway’s Blacksmith Shop, 673 Great Rd., Lincoln.

•Hearthside, 677 Great Rd., Lincoln.

•Slater Mill Historic Site, 67 Roosevelt Ave., Pawtucket.

•Valentine Whitman Jr. House, 1147 Great Rd., Lincoln.

EAST BAY:

•Blithewold Mansion, Gardens & Arboretum, 101 Ferry Rd., Bristol.

•Bristol Statehouse, 240 High St., Bristol.

•Coggeshall Farm, 1 Colt Drive, Bristol.

•Hunt House Museum, Hunt’s Mill Road, East Providence.

NEWPORT:

•Whitehorne House, 416 Thames St., Newport.

•Wilbor House, 548 West Main Rd., Little Compton.

PROVIDENCE:

•John Brown House Museum, 52 Power St.

•Governor Henry Lippitt House Museum, 199 Hope St.

•Governor Stephen Hopkins House, 15 Hopkins St.

•The Handicraft Club, 42 College St.

SOUTH COUNTY:

•Gilbert Stuart Birthplace & Museum, 851 Gilbert Stuart Rd., Saunderstown.

•Oliver Watson House, University of Rhode Island campus, Farm House Road, Kingston.

•Pettaquamscutt Historical Society, 2636 Kingstown Rd., Kingston.

•Smith’s Castle, 55 Richard Smith Drive, Wickford.

•Westerly Armory, Railroad Avenue, Westerly.

WEST BAY:

•Clouds Hill Victorian House Museum, 4157 Post Rd., Warwick.

•Joy Homestead, 156 Scituate Ave., Cranston.

•Pawtuxet Valley Preservation & Historical Society, 1679 Main St., West Warwick.

•Governor Sprague Mansion, 1351 Cranston St., Cranston.