Roma received national recognition for its unique history and architecture when 15 blocks were designated as the Roma Historic District in 1972 and listed in the National Register of Historic Places, and when the central core was designated a National Historic Landmark District in 1993, a distinction held by fewer than 2,500 properties and recognizing Roma as the only intact settlement in the United States derived from the Spanish colonization efforts of José de Escandón and as a living catalog of 19th century architecture and building technologies in the lower Rio Grande region, including Heinrich Portscheller's distinctive molded brickwork. In 1848, the García Sáenz family laid out the town on parts of their porciones, with 15 square blocks and a long, broad avenue perpendicular to the bluffs that became a plaza and the center of commercial and social life, where businessmen traded goods and wealthy merchant families built their homes. This long avenue-style plaza was less common than the typical city block-style plaza, though more common in Texas and also seen in Rio Grande City and Austin. At the end of the plaza opposite the river, Nuestra Señora del Refugio Church was built in 1856. From 1848 to 1900, the Vale-García, Cox, Ramírez, Guerra, and Sáenz families built walled family compounds with storefronts facing the plaza and living spaces above and behind, using wrought iron balconies imported from New Orleans, interiors imported from France, and ornate molded brick designs made locally by the Prussian immigrant Heinrich Portscheller.