[2] City Hall has gone through several renovations, with the most recent overhaul gutting the interior to upgrade it to modern seismic and safety standards.

"[3]: 146 [6] The city purchased the block in 1890 for $100,000, and construction began in 1892, but was halted due to dissatisfaction with the design.

[3] This board terminated Hefty and hired the architectural firm of Whidden and Lewis to design a new building.

[6] Whidden & Lewis designed a four-story structure in a neo-Renaissance style that included a clock tower.

[6] Designed to be located in the center portion of the building, the tower was to rise five-stories above the rest of City Hall with a total height of 200 feet.

[10] City Hall was built with un-reinforced masonry walls and slurry concrete floors to save on costs.

[14] William S. Mason was the first Portland mayor in the new City Hall, with a total of 34 people working in the building at opening.

[15] The Southern Pacific Railroad's 1868 west side rail line ran down Fourth Avenue past City Hall and the county courthouse.

[16] The city and county governments fought the railroad to remove the dirty and noisy steam locomotives from this route, succeeding in 1912.

[16] In 2007, work began on adding light rail tracks on Fifth Avenue for the planned MAX Green Line,[17] and trains once again ran past City Hall starting in 2009.

In 1902, two Port Orford cedar trees were planted on the east side of City Hall.

[7] During this construction the second light well was filled in for more space, and a penthouse apartment was built on top of the roof.

The ten ton Wallula Stone was discovered in the Columbia River Gorge, and was covered with petroglyphs.

[21] The old elevators inside were replaced again in 1946, and in 1948 a runaway truck destroyed part of the stone railing on the Fifth Avenue side, which was then fixed.

[7] In the early morning hours of November 21, 1970, a dynamite-fueled bomb exploded underneath the portico, doing $170,000 in damage.

[23] Later in the decade, Portland upgraded City Hall by adding fire sprinklers and smoke detectors.

[23] The following year the rooftop penthouse was converted into an employee break room that included an outdoor deck.

[25] Previously, the landscaped yard surrounding the building had been paved to allow the city council members to park their vehicles on site.

[26] In 1994, proposals were made to remodel and update the structure to meet modern building codes, with an estimated cost of $16 million.

[28] The estimated $22-million project was proposed due to the building failing to comply with the city codes for earthquakes and fires.

Other changes included the addition of central air conditioning, insulation of the roof and exterior walls, and the replacement of the old single-pane windows.

[42] Reasons given for the additional costs varied from new problems uncovered during the remodel, a booming construction market at the time, and delays in starting the project.

[41] Financing of the renovations came from local bonds, with approximately $3 million per year coming from the general fund to pay the debt off.

[44] Portland City Council chambers occupy the two other floors inside of the rotunda, on the east side of the building.

[9] The building features dentil molding where the roof meets the walls, and the fourth floor has a balcony with paired Tuscan columns on the west side.

[44] Inside the High Renaissance building, the columns of the lobby are covered with a fake marble coating called Scagliola.

[46] Artwork in the building includes works by Norie Sato,[47] a mural by Michael Brophy in the Council Chamber,[48] a constantly changing work called the "Visual Chronicle of Portland" located on the main floor, and changing exhibits.