<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><Version>2.2.0.25</Version><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><ReportLongName>10601 - Disclosure - Restricted Cash</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelColumn>false</LabelColumn><CurrencyCode>USD</CurrencyCode><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName>1/1/2010 - 12/31/2010
USD ($)

USD ($) / shares

</KeyName><CurrencySymbol>$</CurrencySymbol><contextRef><ContextID>Duration_1_1_2010_To_12_31_2010</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0001067063</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2010-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2010-12-31T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS><UnitProperty><UnitID>Unit1</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema><MeasureValue>USD</MeasureValue><MeasureNamespace>iso4217</MeasureNamespace></StandardMeasure><Scale>0</Scale></UnitProperty><UnitProperty><UnitID>Unit13</UnitID><UnitType>Divide</UnitType><NumeratorMeasure><MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema><MeasureValue>USD</MeasureValue><MeasureNamespace>iso4217</MeasureNamespace></NumeratorMeasure><DenominatorMeasure><MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema><MeasureValue>shares</MeasureValue><MeasureNamespace>xbrli</MeasureNamespace></DenominatorMeasure><Scale>0</Scale></UnitProperty><UnitProperty><UnitID>Unit12</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema><MeasureValue>shares</MeasureValue><MeasureNamespace>xbrli</MeasureNamespace></StandardMeasure><Scale>0</Scale></UnitProperty></UPS><CurrencyCode>USD</CurrencyCode><OriginalCurrencyCode>USD</OriginalCurrencyCode></MCU><CurrencySymbol>$</CurrencySymbol><Labels><Label Id="1" Label="12 Months Ended" /><Label Id="2" Label="Dec. 31, 2010" /></Labels></Column></Columns><Rows><Row><Id>2</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><Level>0</Level><ElementName>us-gaap_RestrictedCashAndInvestmentsAbstract</ElementName><ElementPrefix>us-gaap</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><ShortDefinition>No definition available.</ShortDefinition><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsSubReportEnd>false</IsSubReportEnd><IsCalendarTitle>false</IsCalendarTitle><IsTuple>false</IsTuple><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole /><FootnoteIndexer /><Cells><Cell><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><NonNumericTextHeader /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell></Cells><OriginalInstanceReportColumns /><Unit>Other</Unit><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><ElementDefenition>No definition available.</ElementDefenition><IsTotalLabel>false</IsTotalLabel><IsEPS>false</IsEPS><Label>Restricted Cash</Label></Row><Row><Id>3</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><Level>0</Level><ElementName>us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTextBlock</ElementName><ElementPrefix>us-gaap</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><ShortDefinition>No definition available.</ShortDefinition><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsSubReportEnd>false</IsSubReportEnd><IsCalendarTitle>false</IsCalendarTitle><IsTuple>false</IsTuple><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>verboselabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;div&gt;

&lt;div&gt;

&lt;div&gt;

&lt;table style="font-family: Times New Roman; font-size: 10pt;" cellspacing="0" cellpadding="0" width="100%"&gt;
&lt;tr valign="top"&gt;&lt;td style="width: 18pt;" align="right"&gt;

&lt;div&gt;&lt;font style="display: inline; font-family: Times New Roman; font-size: 10pt; font-weight: bold;" class="_mt"&gt;6.&amp;nbsp;&amp;nbsp;&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;
&lt;td&gt;

&lt;div style="text-indent: 0pt; margin-left: 0pt; margin-right: 0pt;" align="justify"&gt;&lt;font style="display: inline; font-family: Times New Roman; font-size: 10pt; font-weight: bold;" class="_mt"&gt;&lt;font style="display: inline; text-decoration: underline;" class="_mt"&gt;RESTRICTED CASH&lt;/font&gt;&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;&lt;/div&gt;

&lt;div style="text-indent: 0pt; display: block;"&gt;&lt;br /&gt;&lt;/div&gt;

&lt;div style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;" align="justify"&gt;&lt;font style="display: inline; font-family: Times New Roman; font-size: 10pt;" class="_mt"&gt;Restricted cash includes security deposits for certain of the Company's properties, and escrow and reserve funds for debt service, real estate taxes, property insurance, capital improvements, tenant improvements, and leasing costs established pursuant to certain mortgage financing arrangements, and is comprised of the following:&amp;nbsp;&amp;nbsp;&lt;font style="font-style: italic; display: inline;" class="_mt"&gt;(dollars in thousands)&lt;/font&gt;&lt;/font&gt;&lt;/div&gt;

&lt;div style="text-indent: 0pt; display: block;"&gt;&lt;br /&gt;&lt;/div&gt;

&lt;div&gt;

&lt;table style="font-family: Times New Roman; font-size: 10pt;" cellspacing="0" cellpadding="0" width="100%"&gt;
&lt;tr&gt;&lt;td valign="top" width="70%"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;&amp;nbsp; &lt;/font&gt;&lt;/td&gt;
&lt;td style="text-align: center;" valign="top" width="24%" colspan="2"&gt;

&lt;div style="text-align: center;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;December 31,&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td style="border-bottom: black 2px solid;" valign="top" width="70%"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;&amp;nbsp; &lt;/font&gt;&lt;/td&gt;
&lt;td style="border-bottom: black 2px solid; text-align: right;" valign="top" width="14%"&gt;

&lt;div style="text-align: right; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 8.1pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;2010&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;
&lt;td style="border-bottom: black 2px solid; text-align: right;" valign="top" width="16%"&gt;

&lt;div style="text-align: right; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 8.1pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;2009&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td valign="top" width="70%"&gt;

&lt;div style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;" align="justify"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;Security deposits&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;
&lt;td valign="top" width="14%" align="right"&gt;

&lt;div style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 8.1pt;" align="right"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;$&amp;nbsp;&amp;nbsp;&amp;nbsp;6,995&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;
&lt;td valign="top" width="16%" align="right"&gt;

&lt;div style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 8.1pt;" align="right"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;$&amp;nbsp;&amp;nbsp;&amp;nbsp;8,618&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td style="border-bottom: black 2px solid;" valign="top" width="70%"&gt;

&lt;div style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;" align="justify"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;Escrow and other reserve funds&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;
&lt;td style="border-bottom: black 2px solid; text-align: right;" valign="top" width="14%"&gt;

&lt;div style="text-align: right; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 8.1pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;10,315&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;
&lt;td style="border-bottom: black 2px solid; text-align: right;" valign="top" width="16%"&gt;

&lt;div style="text-align: right; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 8.1pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;12,063&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td valign="top" width="70%"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;&amp;nbsp; &lt;/font&gt;&lt;/td&gt;
&lt;td valign="top" width="14%"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;&amp;nbsp; &lt;/font&gt;&lt;/td&gt;
&lt;td valign="top" width="16%"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;&amp;nbsp; &lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td style="border-bottom: black 3px double;" valign="top" width="70%"&gt;

&lt;div style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;" align="justify"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;Total restricted cash&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;
&lt;td style="border-bottom: black 3px double; text-align: right;" valign="top" width="14%"&gt;

&lt;div style="text-align: right; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 8.1pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;$ 17,310&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;
&lt;td style="border-bottom: black 3px double; text-align: right;" valign="top" width="16%"&gt;

&lt;div style="text-align: right; text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 8.1pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;" class="_mt"&gt;$ 20,681&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;&lt;/div&gt;&lt;/div&gt; &lt;/div&gt;</NonNumbericText><NonNumericTextHeader>6.&amp;nbsp;&amp;nbsp;


RESTRICTED CASH



Restricted cash includes security deposits for certain of the Company's properties, and escrow and reserve funds for debt</NonNumericTextHeader><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell></Cells><OriginalInstanceReportColumns /><Unit>Other</Unit><ElementDataType>us-types:textBlockItemType</ElementDataType><SimpleDataType>string</SimpleDataType><ElementDefenition>Separate disclosure of the cash and cash items which are restricted as to withdrawal or usage. The provisions of any restrictions shall be described in a note to the financial statements. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 95
 -Paragraph 8, 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 02
 -Paragraph 1
 -Article 5

</ElementReferences><IsTotalLabel>false</IsTotalLabel><IsEPS>false</IsEPS><Label>Restricted Cash</Label></Row></Rows><Footnotes /><NumberOfCols>1</NumberOfCols><NumberOfRows>2</NumberOfRows><ReportName>Restricted Cash</ReportName><MonetaryRoundingLevel>UnKnown</MonetaryRoundingLevel><SharesRoundingLevel>UnKnown</SharesRoundingLevel><PerShareRoundingLevel>UnKnown</PerShareRoundingLevel><ExchangeRateRoundingLevel>UnKnown</ExchangeRateRoundingLevel><HasCustomUnits>false</HasCustomUnits><SharesShouldBeRounded>true</SharesShouldBeRounded></InstanceReport>
