The new Ajuda bridge (Nova Ponte da Ajuda) was actually built on both sides by Portugal in 2000 (the old one was closed in 1709 and is mostly in ruins), as well as the road maintenance; because technically Portugal still has a claim on the Olivença region (which is not actively pursued), although many plans were made by both countries to restore the old bridge, it was clear that these implied the recognition of a border between Portugal and Spain and the sovereignty of Spain over the Olivença region. To avoid that, and because Portugal considered important to have a direct connection to the region of Olivença, the new bridge was built in 2000 at the expense of the Portuguese government (on both margins of the river Guadiana), thus restoring the direct connection between Olivença and Elvas, which had been interrupted since 1709.
There are still plans to restore the old bridge for touristic reasons; but because both countries claim that the bridge is part of their respective heritage (even though the bridge was built and maintained by Portugal from 1510 to 1709, having been partially destroyed over and over again, sometimes due to natural causes, sometimes deliberately exploded by the Spanish Army), there seems to be no simple way to figure out a joint agreement without either side losing their claim over the disputed region...

Disputed border since 1815 (does not show on Portuguese military maps, although civilian maps usually show River Guadiana as the _de facto_ border.