"Lot" is the right word in American English, but although it is not unknown in British English it is very unusual. The Oxford Dictionary defines it as:

"5 chiefly North American a plot of land assigned for sale or for a particular use.
http://oxforddictionaries.com/view/entry/m_en_gb0482240?rske...

As this definition indicates, "plot" is the normal equivalent in British English. Estate agents also refer to "units". But I think "plot", which (again according to Oxford) is "a small piece of ground marked out for a purpose such as building or gardening" (http://oxforddictionaries.com/view/entry/m_en_gb0640770#m_en... ) is not the right word for an area measuring 57,213 square metres. The best word to use here, I think, is "site", which can be pretty well any size.

Usually the block number is given before the site/lot/plot number in English.



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Note added at 1 hr (2011-05-25 22:39:11 GMT)
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Hi Christine. I must admit that 57,000 m2 sounds like a lot for a single site! In that case, I'd say "plot" is the word in British English. As I said, UK estate agents talk about "units" as well, but I think the distinction is that "plot" is the piece of land and "unit" is the building standing on it. Since "sitio" seems to me to mean a piece of land here, a "parcela", "plot" seems best.

See here, for example:
http://www.ogilviehomes.co.uk/new-home/overview/development/...

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Note added at 1 hr (2011-05-25 22:39:50 GMT)
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Though I think "site" would still be OK.