The Calvo-Torres and Martinez-Notley houses are the oldest surviving private residences in Guam. The set of structures are Guam's oldest concrete buildings. And the set is the only surviving group of pre-World War II houses in Agana, "the only fragment left of old Agana's urban space." While a few scattered other individual structures survive, all else has been destroyed by World War II, termites, typhoons Karen of 1962 and Pamela of 1976, and other causes. They are also significant for tie to the Spanish colonial era and the use of ifil wood prior to Guam's deforestation.[2]: 3
The Calvo-Torres House is the oldest, with its oldest part dating about 1800. It is approximately 16.6 by 17.6 metres (54 ft × 58 ft) in plan, has ifil framing, and is roofed by original Spanish tile plus later metal roofing. The oldest part, built of manposteria (coral mixed with lime mortar), once hosted a silversmith. A kitchen was added, and, in the 1920s, a concrete addition.[2]
The Rosario House is believed to have been built in the late 1800s. It is a 8.8 by 11.3 metres (29 ft × 37 ft) south-facing "one-and-a-half bodega type" structure.[2]: 6
Part of the Martinez-Notley House was built in 1826. William H. Notley married into the Martinez family. The house is 20.9 by 15.5 metres (69 ft × 51 ft). It is described as having massing and overall character with "strong Spanish overtones"; it is largely surrounded by manposteria walls.[2]: 6–7
The Leon Guerrero House is a 17.7-by-12-metre (58 ft × 39 ft) house started in 1939 but halted by rumors of war, then used as barracks by Japanese personnel during the war, with storage of rice in its lower level. It would have been destroyed after the war but its owner, Leon Guerrero, refused to vacate.[2]: 7
