Last night's viewing - The Dark Ages: an Age of Light, BBC4; Park Avenue: Money, Power and the American Dream, BBC4

For a while now, Dan Cruickshank has been television's paramount Reverential Whisperer, his voice dropping series by series until it has become a rasping shadow of its original form. He does have some competition, though, if the first episode of Waldemar Januszczak's new series The Dark Ages: an Age of Light is anything to go by.

It opened with our presenter crouched on his hands and knees on a castle staircase, lining up a row of toys and trinkets to establish the rough timeline he was going to deal with, from the end of the Roman empire (little bronze emperor) to the Battle of Hastings (Bayeux tapestry fridge magnet, by the look of it). And the whispering was magnificent – a really canonical display of urgent, sotto voce enthusiasm projection. Cruickshank still holds the title I think. Januszczak spent disturbingly lengthy periods talking like a normal human being. But I don't think Dan can afford to be complacent.

The toys-and-trinkets thing is a Januszczak trademark. Either he really hates computer graphics or he just can't bear to be off screen for any longer than is absolutely necessary, because he generally supplies his own graphics, crouching over paper maps or scribbling on walls with a bit of chalk. And he had plenty of opportunity in this account of early Christian art. "Those thoroughly underrated Dark Age creatives", as Januszczak called them, were about to get their due; though, as it turned out, his case paradoxically rested on the derivative and adaptive nature of the work they produced.

The programme was none the less interesting for being slightly self-contradictory, tracing the emergence of a Christian iconography from the pick'n'mix of pagan models that fed into it. It began with the androgynous, beardless Jesus of early mosaics and sculptures – built on an Apollonian model – and ended with the Christ Pantocrator in Monreale in Sicily, which, Januszczak argued, looked to the precedent offered by Roman depictions of Jupiter. Januszczak himself doesn't use terms like "Christ Pantocrator" incidentally. He's more likely to croon "Oooh. He's a big one, isn't he?" when he introduces the colossal statue of Constantine. But this isn't one of those programmes that assumes the audience have just stumbled in and will be driven off by anything resembling an idea. "The mosaic-lovers among you will know Ravenna already," Januszczak said when introducing us to the Church of St Vitale in that town. I'd forgive him an awful lot for that assumption about the congregation he was addressing.

Alex Gibney's documentary Park Avenue: Money, Power and the American Dream was both fortunate and unfortunate in its timing. Unfortunate because if it had preceded the recent American election it would have had a far more incendiary effect on many viewers. Fortunate, I guess, in that your knowledge that the ideologues of unfettered capital had not succeeded in buying the presidency meant that it was unlikely to actually induce a real riot. So, watching the section on Paul Ryan's devotion to Ayn Rand and her creed of pitiless self-interest, you could console yourself with the knowledge that he had not actually prevailed.

Gibney built his film around one address – 740 Park Avenue, one of the most desirable apartment buildings on the planet and home to the hedge-fund billionaires and lobbyists who like to argue that it is the poor and needy who are America's biggest problem, rather than their own cosseted exemption from the rules everyone else is subject to. Bailed out when their gambles fail, taxed at a lower rate than a gas-station attendant, they insist on the reality of the American Dream while personifying its failure. One statistic nailed it. The US, built on the promise that anyone can drag themselves out of poverty if they work hard enough, actually has lower social mobility than most other comparable democracies.