The Mirage

You'll find this odd little structure right on Mablethorpe's seafront, and it's the sort of thing that makes you do a double-take. The Mirage is essentially a Victorian-era folly - a brick tower that creates an optical illusion when viewed from certain angles along the beach. It's deliberately designed to appear to shimmer and shift as you walk past it, a playful trick of perspective that entertained seaside visitors for generations.

It's more of a curiosity than a major attraction, to be honest. You won't spend hours here - five minutes of examining it from different vantage points is usually enough - but it's the kind of quirky, low-key sort of thing that breaks up a beach walk nicely. Families with older kids might find the optical illusion interesting enough to puzzle over, though younger children may not see what the fuss is about.

The beauty of it is that it's free and demands nothing from you except a bit of wandering along the promenade. It's a perfect stop-off if you're staying at one of the caravan parks dotted around Mablethorpe - the Camping and Caravanning Club Site or Haven Golden Sands are basically on your doorstep. Pop down here before breakfast or after tea, have a wander, try to work out why it looks different from each angle, then head back.

Lincolnshire's coast won't blow your mind, but spots like this remind you why British seaside holidays have their own particular charm. It's unpretentious and a bit daft in the best possible way.