In a hill not far from the castle, there's a small fortification that was recently recovered, the Revelim of St. Anthony. With a chapel, and a windmill, this is also the main reception point for tourists, with a new centre to explain the territory.
The Guadiana International Bridge was built in 1991 by a consortium of Spanish and Portuguese over the river Guadiana that forms the border between the two countries. It is one of the longest bridges in Spain and the third longest bridge in Portugal after the Basque de Gama Bridge and 25th of April Bridge, both in Lisbon.
From Tavira take the old road EN125 in direction to Villa Real de San Antonio (VRS to Antonio as you will find on the signs), you will pass through some little villages that may deserve your attention, we try always to look for the brown signs that indicate a tourist point ;-)
Once we arrived to Vila Real we stopped for a photography of the other side of the Guadiana, yes the Spanish side, I though you could see better, but well it was not bad.
The best was the quick stop on one side of the road to see the Salinas just outside the city in direction to Castro Marim, there were a few flamingos.
You do not have to pay to enter at the castle of Castro Marim, but as usual in most of the Algarve castles, you can only see the walls. The problems is to get there. If oyu follow the road signs and drive a normal car you better have the car full insurance! We are lucky to go with a 4x4, better leave the car down and walk up.
From Castro Marin take the EN122 in direction North, turn right at the exit to Foz de Odelite (ok if you cross the bridge over the Odeleite dam, it means you have passed the exit LOL, that is worth as it is a beautiful lake.) It is a bad road but normally goes empty so it is very nice drive through the country side. At Foz de Odelite you will have great views of the Guadiana, but also all over the road till Alcoutim.
You can find a detail plan of this itinerary at the tourist office where they tell you all the roman villa reminds on the area, but once you arrive there, there is no sign so you have to ask locals to get there …. We did not had so much time so we stopped for occasional photography and got our way up to Alcoutim.