The Houston Medical Building at the University of Texas MD Anderson Cancer Center simply refused to come down Sunday morning, as dense fog delayed the originally scheduled 7:52 a.m. implosion for hours.

But at 11:15 a.m. sharp, the warning sirens blared and a series of explosions ripped through the aging office tower. After an eerie moment of silence, the building collapsed into a massive cloud of brown dust.

As the skies cleared 10 minutes later, only a surprisingly small pile of rubble remained, neatly situated yards from neighboring buildings. The site is planned for a new park and advanced clinical building.

MD Anderson offered an exclusive view of the historic demolition behind the natural density-filtered glass of its observation deck on the 24th floor of the Albert B. and Margaret M. Alkek Hospital.

Members of the press and an array of MD Anderson employees shared fond and not-so-fond memories of the Houston Medical Building (HMB), which opened in 1952 as a regional office for Prudential Insurance. In 1974, the University of Texas acquired the 20-story building to house its executive and administrative staff.

Despite pleas from the Houston preservation community, MD Anderson determined the structure's cracking foundation too costly to merit a full-scale renovation effort. In April 2010, HMB was officially closed.

"This building was a beehive of activity in the 1970s, but it lost its usefulness over the years," said Steve Stuyck, MD Anderson's vice president of public affairs, who started working in the facility upon its acquisition by UT.

"I really dragged my feet when we had to leave," he noted. "We all have great memories of this place."

Nevertheless, he admitted, the building did demand a degree of understanding from its tenants. Those officing at HMB in its later years recalled a perpetual musty smell, poorly lit corridors and a quirky heating and cooling system.

Greg West, director of production for UT Television at MD Anderson, started working in the building in 1994, using office space in the penthouse suites which once housed KHOU before the station relocated to Allen Parkway in 1960. (Some suspect a young Dan Rather, who started with KHOU in 1959, may have walked the same halls at some point.)

But West's fondest memories came from the facility's heyday, when Prudential still maintained most of the floors.

"I used to visit some friends who worked in the building years before I arrived," he said. "It was something back then — a huge cafeteria, tennis courts, an olympic-sized pool."

Removal of remaining materials from the site is expected to be complete by late summer. About 6,000 tons of steel from the building is expected to be recycled. Much of the facility's furniture and fixtures will be reused in other state institutions.