Whiteboard
Whiteboards became commercially available in the early 1960s, but did not become widely used until 30 years later. Early whiteboards needed to be wiped with a damp cloth and markers had a tendency to leave marks behind, even after erasing the board. Dry-erase markers for whiteboards were invented in 1975.
White House
Construction of the White House began with the laying of the cornerstone on October 13, 1792, although there was no formal ceremony. The main residence, as well as foundations of the house, were built largely by enslaved and free African-American laborers, as well as employed Europeans. Much of the other work on the house was performed by immigrants, many not yet with citizenship. The sandstone walls were erected by Scottish immigrants, employed by Hoban, as were the high-relief rose and garland decorations above the north entrance and the "fish scale" pattern beneath the pediments of the window hoods. There are conflicting claims as to where the sandstone used in the construction of the White House originated. Some reports suggest sandstone from the Croatian island of Brač (specifically the Pučišća querry whose stone was used to build the ancient Roman palace of Emperor Diocletian) was used in the original construction of the building, contrarily researchers believe limestone from the island was used in the 1902 renovations and not the original construction. Others suggest the original sandstone simply came from Aquia Creek in Stafford County, Virginia, as importing the stone would be too costly. The initial construction took place over a period of eight years, at a reported cost of $232,371.83 (equal to $ today). Although not yet completed, the White House was ready for occupancy circa November 1, 1800.