2 a : gate, door b (1) : end, boundary; specifically : the end of a runway

Puede ser...

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Note added at 20 mins (2010-02-24 22:09:24 GMT)
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si tomamos portal como entrada, puerta:

portal.

(De puerta).

1. m. Zaguán o primera pieza de la casa, por donde se entra a las demás, y en la cual está la puerta principal.

La definición en inglés es de Merriam Webster y esta en español de la RAE

offers several possibililities

I am taking this idea from the spacious covered entrances of the American White House than include room for arriving in a car (I don't know if it fits your situation): After the fire, President James Madison resided in The Octagon House. Meanwhile, both architect Benjamin Henry Latrobe and Hoban contributed to the design and oversight of the reconstruction, which lasted from 1815 until 1817. The south portico was constructed in 1824 during the James Monroe administration; the north portico was built six years later.[12] Though Latrobe proposed similar porticos before the fire in 1814, both porticos were built as designed by Hoban.[25] The similarity between the South Portico and an elliptical portico, with nearly identical curved stairs at Château de Rastignac in La Bachellerie, France is speculated as the source of inspiration,[26] although this matter is one of great debate.[27] Italian artisans, brought to Washington to help in constructing the U.S. Capitol, carved the decorative stonework on both porticos. The North Portico was not modeled on a similar portico on another Dublin building, the Viceregal Lodge (now Áras an Uachtaráin, residence of the President of Ireland), for its portico postdates the White House porticos' design.[26] For the North Portico, a variation on the Ionic Order was devised incorporating a swag of roses between the volutes. This was done to link the new portico with the earlier carved roses above the entrance.http://en.wikipedia.org/wiki/White_House



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Note added at 15 hrs (2010-02-25 13:24:04 GMT)
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Please excuse the slip into Spanish - should be "porch" not "porche".

I think it can still be a hallway, even if a car (and in earlier days a carriage) can drive through to park at the back of the building.

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Note added at 17 hrs (2010-02-25 15:02:55 GMT)
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Not al all, ufz, in Paris, again, the first thing you will come across when you have crossed the threshold is the office of the concierge, before you can get to the stairs or lift.