This East Dallas strip has the city's best representations of two distinct periods. On lower Swiss Avenue (2900 block), nearer to Downtown, the Wilson Block Historic District is an unaltered block of turn-of-the-20th-century frame houses restored as offices for nonprofit groups. Set-back Prairie Style, Italian Renaissance, Tudor, and Colonial Revival mansions are common in the Swiss Avenue Historic District, the city's first historic district (designated in 1973). Park anywhere along Swiss Avenue in the 4900–6000 blocks, and walk down the tree-shaded street to admire the grand homes and beautifully landscaped yards. Residents and their household staffs are accustomed to folks stopping to gawk or take photos—but do respect their privacy and stay on the sidewalk.