Various dimensions have been given for this temple. Excavations by Keramopoullos in the early part of the 20th century give the dimensions as 21.6m by 9.3 meters. This appears to be the measurement of the cella rather than the overall stylobate. Other excavations were conducted by Bucknell University in cooporation with the Greek State archaeologist, but I have not seen the results. The website "The Megalithic Portal" give the general temple size as 21 x 30 meters which seems more realistic for a temple with 6 x 12 columns. Woodward give the temple size as 46.25 x 22.82 meters, as this is clearly the foundation measurements and not the stylobate. The temple reconstruction plan followes that of Woodward.
The temple of Apollo Ismenios is located on a small hill overlooking the town of present day Thebes. The Mycenaean Palace, or Kadmeion, dates from the 13th century BC and centrally located on the acropolis of the fortified city. The palace contained clay tablets in Linear B, Cretan stirrup jars, and amphorae. Southeast of the city, near the Electran Gates, stood the temple of Apollo Isminios at a location site used from the Geometric period where Mycenean remains have been unearthed including chamber tombs and three cemetaries. The temple site shows three building phases according to the informaton provided by the Archaeological Museum of Thebes. "The first was constructed at the end of the 8th century BC and, after it was destryoed, was replaced by another temple in the Doric style during teh Archaic period, which survived until the beginning of the 4th cnetury BC. Then the third temple was buillt, a Doric kiosk, which was most likely never completed. It is to this that the remians of foundations visible today on the top of the hill belong."