Once upon a time, Ayamonte was the Spanish town where the Portuguese in Algarve went to buy candies (Spanish "caramelos" were a reference, and, together with the cheaper shrimps, a good pretext to cross the river).
Now, there's a bridge, and Portuguese keep crossing the river, with a new purpose - to refuel their cars.
What to see in Ayamonte?
Well... maybe... you know... ... Portugal, just across the river!
Seafood and stuff to Portuguese
In the "good old days" Ayamonte was famous among the Portuguese for selling seafood at a very cheap price.
We Portuguese are better than Spanish cooking seafood, so many people bought there to cook at home.
The prices normalized, and today the visitors prefer to eat in location just to taste the different tastes.
Commerce is not so strong anymore, but buying abroad keeps being a temptation.