In 1853, the two men established a fruit and confectionery store, Dekum & Bickel, which prospered for the next quarter-century in downtown Portland.
Amassing wealth from the "largest wholesale fresh-fruit business in the Northwest", Dekum joined "the frenzied real-estate speculations of the early 1860s", and his large holdings included several buildings that bore his name.
In 1875, he and Simeon Reed financed the city's most expensive building of the time; it was  known as the Dekum and Reed Block.

Portland historian Joseph Gaston wrote, "It is an interesting and noteworthy fact that he was connected with the construction of every building in whole or in part between First and Third on Washington street... ".
These projects included the first large brick building on Front Street, the Gadsby and Commercial blocks, the Waldo Building, and in 1892 the Dekum Building.

The latter, at the southwest corner of Southwest Third Avenue and Washington Street, is eight stories high, was built entirely of Oregon materials, and cost $300,000 in 1892 dollars.
The first three stories of the Romanesque structure are of rough-cut sandstone; the top five floors are of red brick and unglazed terracotta with floral designs.
Decorative machicolations (openings of the sort used in earlier eras for pouring pitch and dropping rocks on attackers) appear in the parapet at the top of the building.
For eight years starting in 1893 Portland's government was headquartered in this structure, temporarily dubbed the Council Building.
The exterior was renovated in 1987, and the interior opened to the nearby Hamilton Building in the 1990s.
The Dekum Building was added to the National Register of Historic Places in 1980 and is part of the Skidmore/Old Town Historic District.
In 1853, the two men established a fruit and confectionery store, Dekum & Bickel, which prospered for the next quarter-century in downtown Portland. Amassing wealth from the "largest wholesale fresh-fruit business in the Northwest", Dekum joined "the frenzied real-estate speculations of the early 1860s", and his large holdings included several buildings that bore his name. In 1875, he and Simeon Reed financed the city's most expensive building of the time; it was  known as the Dekum and Reed Block.
Portland historian Joseph Gaston wrote, "It is an interesting and noteworthy fact that he was connected with the construction of every building in whole or in part between First and Third on Washington street... ". These projects included the first large brick building on Front Street, the Gadsby and Commercial blocks, the Waldo Building, and in 1892 the Dekum Building.
The latter, at the southwest corner of Southwest Third Avenue and Washington Street, is eight stories high, was built entirely of Oregon materials, and cost $300,000 in 1892 dollars. The first three stories of the Romanesque structure are of rough-cut sandstone; the top five floors are of red brick and unglazed terracotta with floral designs. Decorative machicolations (openings of the sort used in earlier eras for pouring pitch and dropping rocks on attackers) appear in the parapet at the top of the building. For eight years starting in 1893 Portland's government was headquartered in this structure, temporarily dubbed the Council Building. The exterior was renovated in 1987, and the interior opened to the nearby Hamilton Building in the 1990s. The Dekum Building was added to the National Register of Historic Places in 1980 and is part of the Skidmore/Old Town Historic District.
Frank Dekum