A mortgage crisis like the one that has devastated homeowners is enveloping the nation’s office and retail buildings, and few places are likely to be hit as hard as Washington. The foreclosure wave is likely to swamp many smaller community banks across the country, and many well-known properties, including Washington’s Mayflower Hotel and the Boulevard at the Capital Centre in Largo, are at risk, industry analysts say. The new round of financial pain, which some had anticipated but hoped to avoid, now seems all but certain. “There’s been an enormous bubble in commercial real estate, and it has to come down,” said Elizabeth Warren, chairman of the Congressional Oversight Panel, the watchdog created by Congress to monitor the financial bailout.