Architects prepare to herd 60 sheep across Millennium Bridge, as Architecture Week events are held across UK

Lord Rogers and Renzo Piano will herd a flock of sheep over the Millennium Bridge tomorrow in one of the opening events in this year's London Architecture Biennale.

Rogers and Piano will lead 60 sheep over the bridge en route from Borough market to Smithfield market, to connect London's historic "larders" and mark the relationship between London's layout and its food distribution.

The two architects were a last-minute replacement for Lord Foster, who had to pull out of the event because of a "pressing engagement in the USA", according to the organisers.

The London Architecture Biennale, which runs alongside Architecture Week, begins today with a "sermon" by Renzo Piano about his own work, being held in Southwark Cathedral.

Highlights of the 10-day long extravaganza of debates, talks, seminars and film includes a series of Big Breakfasts with speakers including Janet Street-Porter and Boris Johnson.

There is also a "meet the editors" forum, where questions can be put to editors of the industry press, including Building's Denise Chevin. And there will be a debate entitled "What skyline does London want?" with Office for Metropolitan Architecture founder Rem Koolhaas, Foreign Office Architects founder Farshid Moussavi and Kohn Pedersen Fox principal Lee Polisano.

Rogers and Piano will lead 60 sheep over the bridge en route from Borough market to Smithfield market

London might have some of the biggest architects on its programme, but cities across the UK will also enjoy a wide range of talks, walks and workshops as part of Architecture Week.

National events listings reveal that sustainability is high on the agenda. In Hull, Niall McLaughlin's Humber Centre for Excellence in the Built Environment, which promotes energy efficiency in buildings, opens to the public from 16 June.

In Cambridge, AC Architects is running a tour of its new sustainable offices, which boast rainwater collection and natural ventilation, on 22 June.

And in Northumbria on 20 and 22 June, the public is invited to discover the newly opened Pavilion and Visitor Centre designed by Michael Hopkins in the Alnwick Garden.