<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains Summary Financial Information extracted from the Form
N-SAR and the financial statements and is qualified in its entirety by
references to such documents.
</LEGEND>
<SERIES>
<NUMBER> 023
<NAME> NUVEEN NATIONAL INSURED MUNICIPAL BOND FUND - CLASS C
<MULTIPLIER> 1000
<S> <C>
<PERIOD-TYPE> 12-MOS
<FISCAL-YEAR-END> APR-30-2000
<PERIOD-START> MAY-01-1999
<PERIOD-END> APR-30-2000
<INVESTMENTS-AT-COST> 748495
<INVESTMENTS-AT-VALUE> 772320
<RECEIVABLES> 19582
<ASSETS-OTHER> 2235
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 794137
<PAYABLE-FOR-SECURITIES> 15851
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 3660
<TOTAL-LIABILITIES> 19511
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 764178
<SHARES-COMMON-STOCK> 1072
<SHARES-COMMON-PRIOR> 991
<ACCUMULATED-NII-CURRENT> 360
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (13737)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 23825
<NET-ASSETS> 774626
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 48032
<OTHER-INCOME> 0
<EXPENSES-NET> 5531
<NET-INVESTMENT-INCOME> 42501
<REALIZED-GAINS-CURRENT> (13653)
<APPREC-INCREASE-CURRENT> (47069)
<NET-CHANGE-FROM-OPS> (18221)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 502
<DISTRIBUTIONS-OF-GAINS> 21
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 564
<NUMBER-OF-SHARES-REDEEMED> 512
<SHARES-REINVESTED> 29
<NET-CHANGE-IN-ASSETS> (86136)
<ACCUMULATED-NII-PRIOR> 567
<ACCUMULATED-GAINS-PRIOR> 1499
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 3866
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 5596
<AVERAGE-NET-ASSETS> 11090
<PER-SHARE-NAV-BEGIN> 11.05
<PER-SHARE-NII> .47
<PER-SHARE-GAIN-APPREC> (.77)
<PER-SHARE-DIVIDEND> (.47)
<PER-SHARE-DISTRIBUTIONS> (.02)
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 10.26
<EXPENSE-RATIO> 1.38
</TABLE>
