Prepositions

a	at, to		al lado de	beside, alongside of
con	with		alrededor de	around
contra	against		cerca de	near, close to
de	of, from		lejos de	far from
en	in, on		delante de	in front of
entre	between, among		debajo de	below, under
hacia	towards, about		en frente de	opposite
para	for, in order, by		detrás de	behind
por	for, through, along, via		encima de	above, on top of
sobre	on, over		hasta	till, until
sin	without		desde	from, since

There are two prepositional contractions with definite articles.  A and el combine to form al, and de and el combine to form del.