Being a sleepy little white village, other than hanging out at cafes or taking a stroll on the gardens of the palace turned pousada nearby, there's hardly much the visitor can occupy himself/herself with as far as a couple hour's outing within Estoi. Except for one site but only if you're the type who finds enjoyment and reward from inspecting a ruin.
Half a kilometer away on the road towards Faro as one leaves Estoi is the Roman ruins of Milreu. This is an easy exploration on foot and because the archeological site is still mostly unpopular, you'd find yourself very possibly one of the only few there, if not, the only visitor walking about examining the rubble. And if you like archeological stuff, there's great interest to be had in Milreu definitely.
Milreu was a relatively vast and sumptuous Roman villa complex which served as a summer residence for wealthy families from Faro down on the coast. I could not find any reliable source/answer to my inquiry when I visited Milreu that time as to what and how the name Milreu took its origins in the first place except from well-documented records stating that it was also called and known to inhabitants in the Algarve as Ossonoba - the very same designation made for the city of Faro. That aside, Milreu has so far been pre-dated to 1st c. AD, well before the Moors had arrived and conquered Southern Portugal.
This archeological site is the most extensive Roman ruins discovered in the entire Algarve region. The Romans had entered and then colonized Portugal since 210 BC. What has been excavated in Milreu so far (an ongoing archeological dig since 1877) are foundations of a peristyle villa consisting of a gallery of marble columns surrounding a courtyard and all round dominated by a temple (later converted into a Christian basilica), baths with fabulous mosaics and changing rooms and a large pool. The well-paved Roman road connecting different villas is intact to this day and one used by visitors to explore the site. A modern building has been erected nearby to house some of the new finds and exhibitions from the digs. A small entrance fee is required to enter Milreu.
A Belgium lady (who spoke Dutch) gave us an explenation of this site. That was very interesting, specially for the kids. After that we visited the site.
The Roman villa from 2e century after Chr. with a bathhouse with mosaic walls, pillars and patio
The Palácio do Visconde de Estói was build in 1840, inspired bij the romantic Pena-slot in Sintra. The entree is free. You can have a look insite and have a look in the gardens