Julius Caesar, Barbican, London <br/> Someone Who'll Watch Over Me, New Ambassadors, London <br/> The Far Pavilions, Shaftesbury, London <br/> Vanishing Points, German Gym, London

The Capitol of Imperial Rome looks like a Norman Foster edifice - a plaza with marble steps leads up to swish plate-glass windows. At the start of Deborah Warner's BITE production of Julius Caesar - which boasts a cast of over 100 including Ralph Fiennes, Simon Russell Beale and Fiona Shaw - it could be the night before a royal walkabout, an election rally, or May Day riots. The place is fenced off with crowd-control barriers but a few plebs are drunkenly loitering and dancing in the street. In fact, as Shakespeare specified, it's approaching the Feast of Lupercal, the fertility festival when Fiennes's Mark Antony is going to offer John Shrapnel's bullish Caesar a non-republican crown.

The Capitol of Imperial Rome looks like a Norman Foster edifice - a plaza with marble steps leads up to swish plate-glass windows. At the start of Deborah Warner's BITE production of Julius Caesar - which boasts a cast of over 100 including Ralph Fiennes, Simon Russell Beale and Fiona Shaw - it could be the night before a royal walkabout, an election rally, or May Day riots. The place is fenced off with crowd-control barriers but a few plebs are drunkenly loitering and dancing in the street. In fact, as Shakespeare specified, it's approaching the Feast of Lupercal, the fertility festival when Fiennes's Mark Antony is going to offer John Shrapnel's bullish Caesar a non-republican crown.

Warner's trendy setting doesn't always sit easily with the text. All the talk of supernatural portents - screeching ghosts, lions in the streets et al - is pretty hard to take from grey-suited bureaucrats. That said, the Bard did throw in his own share of Elizabethan anachronisms. Warner's suits also underline how this study of politicos jockeying for supremacy is timeless. And overall, the arc of a violent revolution is strongly charted here.

In the early scenes, complex motivations for joining in the coup are pinpointed as Anton Lesser's Brutus betrays flashes of power-hungry vanity under his idealistic anger, and as Struan Rodger's Casca exudes the devil-may-care attitude of a bright spark gone to seed. Russell Beale is a particularly riveting Cassius, driven by an almost touching insecurity, a latently homosexual attachment to Brutus, and seething envy. By the end, the battle scenes have produced a vision of epic devastation: a vast, dark hanger strewn with litter and corpses.

In between, though, this production fails to maintain its dramatic grip. Tom Pye's fuzzy video projections are pointlessly distracting and too many of the bit parts are poorly acted. Having stepped in to replace Paul Rhys (who was apparently physically exhausted), Lesser is fiery but never profoundly poignant, while Fiona Shaw, as his wife, has lovely wry tenderness yet overdoes her stage business with a gammy leg.

Fiennes's Antony begins startlingly, racing round in the Lupercal parade like Caesar's favourite party animal/court fool, wearing sports gear and thrusting his crotch at overexcited ladies. After that his transformation into a canny orator seems about as credible as David Beckham becoming a QC, and his great funeral speech falls flat because he doesn't seem to grasp the darkly comic timing of his rhetorical manoeuvres. All in all, an ambitious production which - rather like those Romans - has not realised its full potential.

Someone Who'll Watch Over Me is, perhaps, easier to revive. Frank McGuinness's award-winning 1992 hostage drama focuses on three men in a cell in Beirut. Director Dominic Dromgoole has gathered together a crack trio, with Jonny Lee Miller playing the American Adam, Aidan Gillen as the edgy Irish journalist Edward, and David Threlfall as the new arrival, the nerdy English teacher, Michael.

McGuinness was originally inspired by Brian Keenan and his fellow captives, but his scenario - which is not politically detailed - obviously has fresh reverberations with present troubles in the Middle East. This playwright is, more abstractly, contemplating the historic bonds and hostilities between the three nationalities stuck cheek-by-jowl - the mattresses roughly resemble a map of the Atlantic, with Ireland in the middle. One might argue that, since 9/11, the close alliance McGuinness depicts between the US and Ireland, versus England, needs some updating.

It can also look artificial, with the trio taking distinctly theatrical turns. But this has the structure of musical themes and variations, too. Miller is poignantly gentle, going quietly mad under the strain. Gillen is on superb form, never overplaying his destructive needling. Threlfall at first acts far more doddery than he looks, but he becomes a pricelessly funny pedant and then a man of remarkable, dignified resilience. In the end, it's startling how much McGuinness crams into this little room concerning how we cope with terror and death and each other.

In The Far Pavilions, a musical extravaganza adapted from the novel by M M Kaye, all the conflicts and ententes are between colonial Brits and the peoples of North India and Afghanistan. In this saga, many of Queen Victoria's redcoats are racist snobs, turning particularly nasty on discovering that one of their own - our hero, Ashton Pelham-Martyn - was reared amid the natives. Ashton (aka Ashok) is, of course, culturally torn and outraged by their bigotry, but he happily reunites in the end with his childhood sweetheart, Princess Anjuli.

Some of Kaye's lessons about multi-ethnic societies still apply today. But what a bore this show is! Composer Philip Henderson's plodding tunes make you wonder if he's just working up to playing a scale, and Stephen Clark's lyrics are equally bland. Most of the cast, when faced with a surging crescendo, merely shout, and it seems faintly ridiculous - given the fuss about Ashok - how no one seems to have noticed that half the maharajah's court is made up of white folks masquerading as locals. The only redeeming features are the gorgeous traditional Indian costumes and the electrifying Indian score.

Finally, Vanishing Points was a shockingly lame site-specific promenade show by Complicite's normally inspired Simon McBurney. This was part of a season of events celebrating the writer John Berger.

After queuing outside for three-quarters of an hour, without explanation, you began to imagine this was part of the show and that the director was making some ironic point, as its themes were train stations and immigrants' experiences. But we were then ushered into a girdered warehouse space to watch pretentious video footage of refugees' faces and whizzing railway tracks. This was accompanied by prose and poetry read with irksome, po-faced sententiousness by Berger (a self-conscious performer), his fellow writer Anne Michaels, McBurney, Juliet Stevenson and Paul Rhys. Hang on, I thought he was off work? If only they all were...

'Julius Caesar': Barbican, London EC2 (0845 120 7550), to 14 May; 'Someone Who'll Watch Over Me': New Ambassadors, London WC2 (0870 060 6627), to 18 June; 'The Far Pavilions': Shaftesbury, London WC2 (020 7379 5399), to 4 Sept

k.bassett@independent.co.uk