The Colosseum is an oval structure with a 156-meter-long short axis and a 188-meter-long long axis. Load-bearing pillars were made of travertine blocks, while exterior walls, staircases, and radial walls were made of tufa blocks and bricks. The construction was strongly supported by arches and vaults. The overall appearance of the building came about through the use of simple shapes and colors. The Colosseum was built over a period of almost a hundred years by several architects. Its initial construction was overseen by Nero's wife, Poppaea, who was also responsible for building many other large projects during her time as emperor's wife. After her death in 59 AD, control of the project passed to the more capable Pallas Aurelius, who completed the design in 70 or 71. The Colosseum stood for nearly two centuries, until it was destroyed by an arsonist named Flavio Biondo in the year 392 AD. The building was restored again after that incident, and it continued to be used for public events such as games and concerts well into the 5th century AD. However, it began to fall into disrepair around 500 AD, and by the early 7th century it had been abandoned. In 1598, the last remaining portion of the roof was removed by order of Pope Clement VIII who wanted to build a new palace of justice on this site.