You may have noticed a charming irony of Lottery funding: when the cheque goes out, the lucky arts organisation hands it straight to a firm of builders and closes down for as long as it takes to get its premises refurbished. Far from increasing the cultural supply, the Lottery seems to be stopping things dead in their tracks.

In America they have an answer to this sort of problem. Whatever the cash source, when it comes and the premises get their new look, it tends not to send the entire operation into shut-down. A shining example of how it's done is the Chicago Symphony Orchestra, in whose company I spent last weekend.

The Chicago Symphony has its own home, Orchestra Hall, which occupies a prime site on the city's downtown Loop. For the past three years the Hall has been undergoing a radical transformation into what will open this October as Symphony Center - refurbished, extended, with new audience and backstage facilities, all rather like what's happening at Covent Garden. But it hasn't involved so much as a day's lost playing or a night's lost listening. All the work has been done (and continues at this moment) in intensive, round-the-clock assaults during the summer months, cosmetically patched over for the starts of each new autumn season. And during the summer months the Chicago Symphony simply decamps to its other home - in an outer-Chicago suburb that from June to September hosts the Ravinia Festival.

Summer homes are a long-established tradition for American orchestras, and although the terms of their residence vary, the ideology is standard, governed by the same vestigial pioneer mentality that sends Americans away on hunting weekends to log cabins in the Appalachians. The setting is informal, countrified, relaxed, in varying ways open to the elements. And at Ravinia that means a giant bandstand in a park, where the orchestra plays in short-sleeved shirts to an open, fan-shaped auditorium of 3,000 with another six or seven thousand picnicking around it.

If you've been to Kenwood, or the "Land of Hope and Glory" concerts that take place in British stately homes, you'll know the atmosphere. But at Ravinia the artistic stakes are higher. At Ravinia you get Thomas Hampson, Pinchas Zukerman and Sarah Chang. You also get demanding programmes, without fireworks. And, night after night for a substantial proportion of the festival's 11-week run, you get what many listeners believe to be America's finest orchestra.

Chicago's standing in the Ivy League of US bands tends to be qualified by opinions of its chief conductor, Daniel Barenboim, who took on the job in 1991 after Georg Solti had occupied it for some 30 years. Solti's reign was seen by many as a golden era; Barenboim proved an unpopular substitute. The orchestra didn't like him; the local press ran an "Anyone but Barenboim" campaign; sharp-eared local audiences dismissed his conducting as self-indulgently superficial. They still do.

But things have settled down. Barenboim still has enemies, but he's cultivated friendships too. Enough to have been re-hired for three more years. And from what I heard last weekend, the orchestra is in good shape. The acoustics of Ravinia's open pavilion are not ideal: the sound is unfocused, slightly raw. But the size and textural richness of the playing was impressive - this is unmistakably a powerhouse orchestra - with full- weight strings and cultivated wind. You could put them in a field and they'd make handsome listening.

I should add, though, that Barenboim has nothing to do with the orchestra's appearances at Ravinia - which is actually a free-standing festival that invites the orchestra to take up residence. It has its own administrator, Zubin Mehta's brother Zarin, and its own music director, the pianist/conductor Christoph Eschenbach. Eschenbach is the man who, for the duration of the residency, wields the baton - as well as doing just about everything else Ravinia asks, short of selling popcorn. In a staggering display of energy last weekend he conducted three substantial orchestral concerts, played a Beethoven piano concerto, took part in a four-hand keyboard recital and shared a chamber platform with the Takacs Quartet. Whatever he takes to stay awake, it sure works.

Not everything was flawless in these densely packed performances. On one night Eschenbach directed from the piano a frenetically untidy Beethoven 1st Concerto, followed by a choppy Brahms 4th Symphony. But the next night was better - perhaps because he brought in another pianist, Peter Serkin, for Mozart's C Major Concerto K467. It was one of the more memorable accounts of that piece I've heard, beautifully phrased by Serkin, who articulates with clean but meaningful precision through the slowest of legatos.

The other memorable thing of the evening was Eschenbach's bravery in starting the programme with Ligeti's landmark of the Sixties avant-garde, Atmospheres. With its subtly swelling and evaporating cluster chords, sustained through long durations, it's not everyone's idea of music for an audience of picnickers. And random interventions from passing trains supplied surprise sonorities that the composer never dreamt of. But for all that, it pulled through with inexplicable intensity. And that it happened at all was an example of the seriousness with which Eschenbach approaches the business of programming this otherwise popular festival.

Another example was the mini-theme of Transcriptions which dominated last weekend's concerts. There was Liszt's orchestration of Schubert's "Wanderer" Fantasy, with a self-conscious but deeply responsive young Mexican pianist, Alejandro Vela, as the soloist. There was Joseph Joachim's enlargement into a "symphony" of Schubert's symphonically ambitious Grand Duo (followed by Eschenbach and Vela making for a nearby piano and playing the Duo as originally written). And for a fascinating divertissement, there was the British pianist David Owen Norris playing a virtuoso recital of nothing but transcriptions, including Liszt's grotesquely over-decorative takes on Schubert's Winterreise: the musical equivalent of fixing gargoyles to a Le Corbusier. Only the maverick, oddball brilliance of someone like Norris - who standardly fills his programmes with the sort of repertoire other pianists consign to encores - could bring it off.

Another maverick pianist is Stephen Hough who - back in Britain - played Bartk's 3rd Concerto at the Prom on Thursday with Mark Wigglesworth and the BBC National Orchestra of Wales. Bartk 3 isn't every pianist's natural diet: its lean, lucid transparency seems to encompass less than the combative drive of Bartk 1 and 2. You hear it and think something must be missing from the score - beyond the final 17 bars which the composer never lived to complete (they were added by a friend). But this is the sort of music Hough was born to rescue, nurturing its sharp but understated elegance with a finesse and certainty that "finishes" the piece. If Bernard Haitink's Missa Solemnis has been the most profound experience I've had so far at this year's Proms, and last week's Korngold Violanta the most overwhelming, Hough's Bartk was probably the most satisfying. Definitely the most purely musical.