Evan Williams is on the move. The Twitter co-founder and his wife are building a "modern house" and just put their old place, a two-bedroom San Francisco penthouse, on the market for $1.5 million, Curbed reports. Have a look.

Though investors recently valued Twitter at $1 billion, Williams has yet to cash out. Both his old and new place were presumably funded with money and lucrative pre-IPO shares the serial entrepreneur made selling Blogger to Google.

The riches do not appear to have been invested in the penthouse's current furnishings: Either Williams or his stager seem to have ordered the entire Pier 1 catalog right up.

Whatever. A similarly blah getup did not inhibit the sale of the Berkeley home of Williams' fellow co-founder Biz Stone, which has changed hands barely two months after it went on the market.

Pics via McGuire and Curbed.