Riordan Mansion State Historic Park in Flagstaff, Arizona, preserves the unusual duplex home built in 1904 for brothers Timothy and Michael Riordan and their wives, sisters Caroline and Elizabeth Metz, while Arizona was still a territory. Designed by Charles Whittlesey, the large residence joined two similar family wings with a substantial common room, expressing both close kinship and the Riordans’ partnership. Its rustic design used log planks, wood shingles, native stone, and massive porch arches to suit the local landscape. The site also reflects the family’s broad influence in northern Arizona business and politics during the territorial period.