these niches are outside the Ufizzi Gallery in Florence
but sometimes they're architectural features in their own right:
Pyramid of the niches, El Tajín, Veracruz, Mexico. Photo by Ernest Mettendorf
Nowadays a niche might hold some other kind of fashionable objet d-art - or perhaps, in a bathroom, a small, tastefully expensive group of toiletries.
Quite often, though, all you'll find is dust and the odd expired spider.
Niches can't contain very much because of their size, and because of this the meaning of niche has been extended to describe objects of interest to, or required by, a very few people.
Niche products include crowns, lizard food, and T shirts bearing the slogan I DON'T HAVE A SENSE OF HUMOUR.
On reflection, I realise we all inhabit our own niches.
What's the most niche product you own?
Spot the Frippet: niche. This word comes from the Old French nichier. to nest, from the Latin nīdus, nest.