Big Ben's "bongs" will ring out for the last time on Saturday morning before they fall silent for a month.
Maintenance work will mean the hourly chimes and quarter bells will cease to ring from 0800 BST until September.
The clock itself will stop for a few hours as an alternative system is
installed to keep it working while the work to the bells is carried out.
The maintenance is the second and final phase of a programme of works prior to the clock's 150th anniversary in 2009.
The work will include the replacement of the bearings on the strike train which operates the hour bell and the going train which controls the clock itself.
At 0900 BST on Saturday, a team of specialist "industrial rope access technicians" will abseil down the south clock face to start a day of cleaning and repair.
This work takes place every five years.
Radio 4's PM show, which uses Big Ben's bongs, is asking listeners to suggest alternative songs or tunes it can use while the bells are silenced.