Title: Achaea
Content:  Achaea or Achaia, sometimes transliterated from Greek as Akhaia (Αχαΐα, Akhaïa ), is one of the regional units of Greece. It is part of the region of Western Greece and is situated in the northwestern part of the Peloponnese peninsula. The capital is Patras which is the third largest city in Greece.
Title: Achaea
Content: Aigialeia (2) ; Erymanthos (4) ; Kalavryta (5) ; Patras (Patra, 1) ; West Achaea (Dytiki Achaia, 3)  The regional unit Achaea is subdivided into 5 municipalities. These are (number as in the map in the infobox):
Title: Achaea
Content:  As a part of the 2011 Kallikratis government reform, the regional unit Achaea was created out of the former prefecture Achaea (Νομός Αχαΐας). The prefecture had the same territory as the present regional unit. At the same time, the municipalities were reorganised, according to the table below.
Title: Achaea
Content:   Achaea today has about one-third of the population of the Peloponnese. Patras, the capital of Achaea, is the third largest city in Greece, behind Athens and Thessaloniki. Two-thirds of the Achaean population live near Patras, and more than half within the city limits. The main industrial areas are around Patras.
Title: West Achaea
Content:  West Achaea (Δυτική Αχαΐα – Dytiki Achaia) is a municipality in the Achaea regional unit, West Greece region, Greece. The seat of the municipality is the town Kato Achaia. The municipality has an area of 573.30 km2.
Title: Achaea (ancient region)
Content:  Achaea or Achaia (Ἀχαΐα, Akhaia, ) was (and is) the northernmost region of the Peloponnese, occupying the coastal strip north of Arcadia. Its approximate boundaries were to the south the mountain range of Erymanthus, to the south-east the range of Cyllene, to the east Sicyon, and to the west the Larissos river. Apart from the plain around Dyme, to the west, Achaea was generally a mountainous region.
Title: Achaea (ancient region)
Content:  Achaea was conquered by the Romans in the year 146 BC. Emperor Augustus established Achaea as a senatorial province; generally speaking, the region benefited from the enlightened attitude of Roman emperors such as Augustus. This was because Achaea was geographically closer to Rome than other provinces, and so it was given political advantages and greater status in order for the Roman court to maintain a political equilibrium within the empire. The rule of Achaea in Roman times was placed under the Senate while a proconsul of Praetorian rank was appointed as its governor with the administrative seat in Corinth. However, Rome exercised fairly light control over Achaea: no Roman garrisons were posted 
Title: Regions of ancient Greece
Content:  Geographically, Achaea was (and is) the northernmost region of the Peloponnese, occupying the coastal strip north of Arcardia. To the south, it bordered Arcadia along the ridge of high ground running from Mount Erymanthos to Mount Cyllene. To the east, it bordered Corinthia near to the city of Sicyon, and to the west the Larissos river and western ridge of Erymanthos formed the border with Elis. Apart from the plain around Dyme, to the west, Achaea was generally a mountainous region.
Title: Achaea (constituency)
Content:  Achaea is a constituency of the Hellenic Parliament. It corresponds to Achaea Prefecture and elects eight members of parliament. The members of the prominent Papandreou politician family (Georgios Papandreou, Andreas Papandreou, George Papandreou) come from this constituency.
Title: Achaia (Roman province)
Content:   Achaia, sometimes spelled Achaea,  was a province of the Roman Empire, consisting of the  Peloponnese, Attica, Boeotia, Euboea, the Cyclades and parts of Phthiotis, Aetolia-Acarnania and Phocis. In the north, it bordered on the provinces of Epirus vetus and Macedonia. The region was annexed by the Roman Republic in 146 BC following the sack of Corinth by the Roman general Lucius Mummius, who was awarded the surname "Achaicus" ("conqueror of Achaia"). Initially part of the Roman province of Macedonia, it was made into a separate province by Augustus. Achaia was a senatorial province, thus free from military men and legions, and one of the most prestigious and sought-after provinces for senators 

Question: What is the capital of Achaea Regional Unit?
Answer: Patras.
Patra.
Patrai.