I know. But how do you get the bit the OP needs? Not like this:

perl -MURI 
-E"$u=new URI('http://dspace.mit.edu/handle/1721.1/53720'); say $u->ho
+st"
dspace.mit.edu
[download]

Nor any of these:

c:\test>perl -MURI -E"my $u=new URI('http://dspace.mit.edu/handle/1721
+.1/53720'); say $u->authority"
dspace.mit.edu

c:\test>perl -MURI -E"my $u=new URI('http://dspace.mit.edu/handle/1721
+.1/53720'); say $u->path"
/handle/1721.1/53720

c:\test>perl -MURI -E"my $u=new URI('http://dspace.mit.edu/handle/1721
+.1/53720'); say $u->fragment"


c:\test>perl -MURI -E"my $u=new URI('http://dspace.mit.edu/handle/1721
+.1/53720'); say $u->opaque"
//dspace.mit.edu/handle/1721.1/53720

c:\test>perl -MURI -E"my $u=new URI('http://dspace.mit.edu/handle/1721
+.1/53720'); say $u->canonical"
http://dspace.mit.edu/handle/1721.1/53720
[download]

I'm sorry I thought he wanted host, like

my  $uri = URI->new_abs( $str, $mech->uri )
[download]

, but I would just use follow_link